Problème de mémoire

Bonjour,
J'ai un problème de mémoire et de ralentissement de mon PC. Lorsque je vais sur Gestionnaire des tâches, je me rends compte que svchost.exe au nombre de 7 utilisent 46076 Ko.
J'ai fais une analyse avec Avira Antivir Personal dont voici le rapport :

Avira AntiVir Personal
Report file date: dimanche 28 décembre 2008 18:33

Scanning for 1125477 virus strains and unwanted programs.

Licensed to: Avira AntiVir PersonalEdition Classic
Serial number: 0000149996-ADJIE-0001
Platform: Windows XP
Windows version: (Service Pack 3) [5.1.2600]
Boot mode: Save mode
Username: bureau
Computer name: PC

Version information:
BUILD.DAT : 8.2.0.337 16934 Bytes 18/11/2008 13:05:00
AVSCAN.EXE : 8.1.4.10 315649 Bytes 18/11/2008 08:21:26
AVSCAN.DLL : 8.1.4.0 40705 Bytes 26/05/2008 07:56:40
LUKE.DLL : 8.1.4.5 164097 Bytes 12/06/2008 12:44:19
LUKERES.DLL : 8.1.4.0 12033 Bytes 26/05/2008 07:58:52
ANTIVIR0.VDF : 7.1.0.0 15603712 Bytes 27/10/2008 11:30:36
ANTIVIR1.VDF : 7.1.1.33 1705984 Bytes 24/12/2008 17:19:53
ANTIVIR2.VDF : 7.1.1.34 2048 Bytes 24/12/2008 17:19:54
ANTIVIR3.VDF : 7.1.1.41 116736 Bytes 28/12/2008 17:19:56
Engineversion : 8.2.0.45
AEVDF.DLL : 8.1.0.6 102772 Bytes 14/10/2008 10:05:56
AESCRIPT.DLL : 8.1.1.19 336252 Bytes 28/12/2008 17:20:15
AESCN.DLL : 8.1.1.5 123251 Bytes 07/11/2008 15:06:41
AERDL.DLL : 8.1.1.3 438645 Bytes 04/11/2008 13:58:38
AEPACK.DLL : 8.1.3.4 393591 Bytes 11/11/2008 09:41:39
AEOFFICE.DLL : 8.1.0.33 196987 Bytes 28/12/2008 17:20:13
AEHEUR.DLL : 8.1.0.75 1524087 Bytes 28/12/2008 17:20:12
AEHELP.DLL : 8.1.2.0 119159 Bytes 28/12/2008 17:20:07
AEGEN.DLL : 8.1.1.8 323956 Bytes 28/12/2008 17:20:05
AEEMU.DLL : 8.1.0.9 393588 Bytes 14/10/2008 10:05:56
AECORE.DLL : 8.1.5.2 172405 Bytes 28/12/2008 17:19:57
AEBB.DLL : 8.1.0.3 53618 Bytes 14/10/2008 10:05:56
AVWINLL.DLL : 1.0.0.12 15105 Bytes 09/07/2008 08:40:05
AVPREF.DLL : 8.0.2.0 38657 Bytes 16/05/2008 09:28:01
AVREP.DLL : 8.0.0.2 98344 Bytes 31/07/2008 12:02:15
AVREG.DLL : 8.0.0.1 33537 Bytes 09/05/2008 11:26:40
AVARKT.DLL : 1.0.0.23 307457 Bytes 12/02/2008 08:29:23
AVEVTLOG.DLL : 8.0.0.16 119041 Bytes 12/06/2008 12:27:49
SQLITE3.DLL : 3.3.17.1 339968 Bytes 22/01/2008 17:28:02
SMTPLIB.DLL : 1.2.0.23 28929 Bytes 12/06/2008 12:49:40
NETNT.DLL : 8.0.0.1 7937 Bytes 25/01/2008 12:05:10
RCIMAGE.DLL : 8.0.0.51 2371841 Bytes 12/06/2008 13:48:07
RCTEXT.DLL : 8.0.52.0 86273 Bytes 27/06/2008 13:34:37

Configuration settings for the scan:
Jobname..........................: Complete system scan
Configuration file...............: c:\program files\avira\antivir personaledition classic\sysscan.avp
Logging..........................: low
Primary action...................: interactive
Secondary action.................: ignore
Scan master boot sector..........: on
Scan boot sector.................: on
Boot sectors.....................: C:, D:, L:,
Process scan.....................: on
Scan registry....................: on
Search for rootkits..............: off
Scan all files...................: Intelligent file selection
Scan archives....................: on
Recursion depth..................: 20
Smart extensions.................: on
Macro heuristic..................: on
File heuristic...................: medium

Start of the scan: dimanche 28 décembre 2008 18:33

The scan of running processes will be started
Scan process 'avscan.exe' - '1' Module(s) have been scanned
Scan process 'avcenter.exe' - '1' Module(s) have been scanned
Scan process 'LVCOMSX.EXE' - '1' Module(s) have been scanned
Scan process 'explorer.exe' - '1' Module(s) have been scanned
Scan process 'svchost.exe' - '1' Module(s) have been scanned
Scan process 'svchost.exe' - '1' Module(s) have been scanned
Scan process 'svchost.exe' - '1' Module(s) have been scanned
Scan process 'lsass.exe' - '1' Module(s) have been scanned
Scan process 'services.exe' - '1' Module(s) have been scanned
Scan process 'winlogon.exe' - '1' Module(s) have been scanned
Scan process 'csrss.exe' - '1' Module(s) have been scanned
Scan process 'smss.exe' - '1' Module(s) have been scanned
12 processes with 12 modules were scanned

Starting master boot sector scan:
Master boot sector HD0
[INFO] No virus was found!
Master boot sector HD1
[INFO] No virus was found!
Master boot sector HD2
[INFO] No virus was found!
[WARNING] System error [21]: Le périphérique n'est pas prêt.
Master boot sector HD3
[INFO] No virus was found!
[WARNING] System error [21]: Le périphérique n'est pas prêt.
Master boot sector HD4
[INFO] No virus was found!
[WARNING] System error [21]: Le périphérique n'est pas prêt.
Master boot sector HD5
[INFO] No virus was found!
[WARNING] System error [21]: Le périphérique n'est pas prêt.

Start scanning boot sectors:
Boot sector 'C:\'
[INFO] No virus was found!
Boot sector 'D:\'
[INFO] No virus was found!
Boot sector 'L:\'
[INFO] No virus was found!

Starting to scan the registry.
The registry was scanned ( '53' files ).

Starting the file scan:

Begin scan in 'C:\'
C:\pagefile.sys
[WARNING] The file could not be opened!
C:\emme\Louvre_1\LOUVRE1.exe
[DETECTION] Is the TR/Dropper.Gen Trojan
[NOTE] The file was moved to '49acbfdd.qua'!
C:\System Volume Information\_restore{0B10E335-0AA3-4678-8A42-1164FE6C0012}\RP520\A0133763.exe
[DETECTION] Is the TR/Dropper.Gen Trojan
[NOTE] The file was moved to '4988caf4.qua'!
Begin scan in 'D:\' <sauvegarde>
Begin scan in 'L:\' <WD Passport>

End of the scan: dimanche 28 décembre 2008 20:44
Used time: 2:10:58 Hour(s)

The scan has been done completely.

8251 Scanning directories
514538 Files were scanned
2 viruses and/or unwanted programs were found
0 Files were classified as suspicious:
0 files were deleted
0 files were repaired
2 files were moved to quarantine
0 files were renamed
1 Files cannot be scanned
514535 Files not concerned
5117 Archives were scanned
5 Warnings
2 Notes

et j'ai ensuite réalisé une autre analyse avec Hijack This v2 dont voici le rapport :

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 21:10:18, on 28/12/2008
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16762)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Fichiers communs\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
C:\Program Files\Bonjour\mDNSResponder.exe
C:\Program Files\Java\jre6\bin\jqs.exe
C:\Program Files\Fichiers communs\Nero\Nero BackItUp 4\NBService.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Fichiers communs\BitDefender\BitDefender Communicator\xcommsvr.exe
C:\Program Files\Fichiers communs\BitDefender\BitDefender Update Service\livesrv.exe
C:\Program Files\BitDefender\BitDefender 2008\vsserv.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\System32\svchost.exe
C:\Program Files\BitDefender\BitDefender 2008\bdagent.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\IObit\Advanced SystemCare 3\Sup_SmartRAM.exe
C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://portail.free.fr/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.ustart.org
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://www.update.microsoft.com/windowsupdate/v6/default.aspx
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = *.local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: (no name) - AutorunsDisabled - (no file)
O2 - BHO: Aide pour le lien d'Adobe PDF Reader - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Fichiers communs\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\Spybot - Search & Destroy\SDHelper.dll
O2 - BHO: (no name) - {64466B8E-20A7-4A4A-AFF4-AAD9CA68B52C} - (no file)
O2 - BHO: EoRezoBHO - {64F56FC1-1272-44CD-BA6E-39723696E350} - (no file)
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre6\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Programme d'aide de l'Assistant de connexion Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Fichiers communs\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: BHO Barre de Confiance - {988B07F5-7392-455A-8A1F-64935CB8B6ED} - C:\Program Files\BarreConfCMCIC\TAPBar.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\3.1.807.1746\swg.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre6\bin\jp2ssv.dll
O2 - BHO: JQSIEStartDetectorImpl - {E7E6F031-17CE-4C07-BC86-EABFE594F69C} - C:\Program Files\Java\jre6\lib\deploy\jqs\ie\jqs_plugin.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O3 - Toolbar: Barre de confiance - {55BDF3B0-C0A8-481A-B8A6-01CD2BE0F3FD} - C:\Program Files\BarreConfCMCIC\TAPBar.dll
O3 - Toolbar: BitDefender Toolbar - {381FFDE8-2394-4f90-B10D-FC6124A40F8C} - C:\Program Files\BitDefender\BitDefender 2008\IEToolbar.dll
O3 - Toolbar: Browser Toolbar - {2EEF94DF-75F6-42E9-B7FB-AF5A170A6E2E} - (no file)
O4 - HKLM\..\Run: [BitDefender Antiphishing Helper] "C:\Program Files\BitDefender\BitDefender 2008\IEShow.exe"
O4 - HKLM\..\Run: [BDAgent] "C:\Program Files\BitDefender\BitDefender 2008\bdagent.exe"
O4 - HKLM\..\Run: [MSConfig] C:\WINDOWS\PCHealth\HelpCtr\Binaries\MSConfig.exe /auto
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [SmartRAM] "C:\Program Files\IObit\Advanced SystemCare 3\Sup_SmartRAM.exe" /m
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - HKUS\S-1-5-19\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-19\..\RunOnce: [nlpo_01] cmd.exe /c md "%USERPROFILE%\Local Settings\Temp" (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-19\..\RunOnce: [nlpo_03] rundll32 advpack.dll,LaunchINFSection nlite.inf,S (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-20\..\RunOnce: [nlpo_01] cmd.exe /c md "%USERPROFILE%\Local Settings\Temp" (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'Default user')
O8 - Extra context menu item: Add to Google Photos Screensa&ver - res://C:\WINDOWS\system32\GPhotos.scr/200
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office12\EXCEL.EXE/3000
O9 - Extra button: Trace - {04849C74-016E-4a43-8AA5-1F01DE57F4A1} - C:\WINDOWS\system32\shdocvw.dll
O9 - Extra 'Tools' menuitem: VisualRoute Trace - {04849C74-016E-4a43-8AA5-1F01DE57F4A1} - C:\WINDOWS\system32\shdocvw.dll
O9 - Extra button: Ajout Direct - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Program Files\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra 'Tools' menuitem: &Ajout Direct dans Windows Live Writer - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Program Files\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra button: (no name) - {3B8FB116-D358-48A3-A5C7-DB84F15CBB04} - http://www.expresstoolie.com/redirect.php (file missing)
O9 - Extra 'Tools' menuitem: IExplorer Security - {3B8FB116-D358-48A3-A5C7-DB84F15CBB04} - http://www.expresstoolie.com/redirect.php (file missing)
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\Office12\REFIEBAR.DLL
O9 - Extra button: (no name) - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\Spybot - Search & Destroy\SDHelper.dll
O9 - Extra 'Tools' menuitem: Spybot - Search & Destroy Configuration - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\PROGRA~1\Spybot - Search & Destroy\SDHelper.dll
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O16 - DPF: {5ED80217-570B-4DA9-BF44-BE107C0EC166} (Windows Live Safety Center Base Module) - http://cdn.scan.onecare.live.com/resource/download/scanner/wlscbase5036.cab
O16 - DPF: {867E13F2-7F31-44FB-AC97-CD38E0DC46EF} - https://www.touslesdrivers.com/index.php?v_page=29
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsPAClient.cab56907.cab
O16 - DPF: {DE625294-70E6-45ED-B895-CFFA13AEB044} (AxisMediaControlEmb Class) - http://lecroqburger.dvrdns.org/activex/AMC.cab
O20 - Winlogon Notify: !SASWinLogon - C:\Program Files\SUPERAntiSpyware\SASWINLO.dll
O22 - SharedTaskScheduler: disaffiliation - {854b8525-c907-4258-bc2e-7b118037419c} - (no file)
O23 - Service: Apple Mobile Device - Apple, Inc. - C:\Program Files\Fichiers communs\Apple\Mobile Device Support\bin\AppleMobileDeviceService.exe
O23 - Service: Ati HotKey Poller - ATI Technologies Inc. - C:\WINDOWS\system32\Ati2evxx.exe
O23 - Service: ATI Smart - Unknown owner - C:\WINDOWS\system32\ati2sgag.exe
O23 - Service: Service Bonjour (Bonjour Service) - Apple Inc. - C:\Program Files\Bonjour\mDNSResponder.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Sun Microsystems, Inc. - C:\Program Files\Java\jre6\bin\jqs.exe
O23 - Service: BitDefender Desktop Update Service (LIVESRV) - BitDefender SRL - C:\Program Files\Fichiers communs\BitDefender\BitDefender Update Service\livesrv.exe
O23 - Service: Nero BackItUp Scheduler 4.0 - Nero AG - C:\Program Files\Fichiers communs\Nero\Nero BackItUp 4\NBService.exe
O23 - Service: Remote Packet Capture Protocol v.0 (experimental) (rpcapd) - CACE Technologies - C:\Program Files\WinPcap\rpcapd.exe
O23 - Service: BitDefender Virus Shield (VSSERV) - BitDefender S.R.L. - C:\Program Files\BitDefender\BitDefender 2008\vsserv.exe
O23 - Service: BitDefender Communicator (XCOMM) - BitDefender - C:\Program Files\Fichiers communs\BitDefender\BitDefender Communicator\xcommsvr.exe