Excellent ordi qui rame --'

Bonjour,
j'ai acquéris, l'été dernier, un ordinateur qui ma foi est plutôt correct. Ce que je ne comprends pas, c'est qu'au début, il fonctionnait très bien, mais depuis un certain temps il rame rame rame ... et bug. J'ai fait un scan antivirus via Kaspersky qui n'a bien évidemment rien détecté. Par la suite, j'ai fait un scan via Hijackthis et voici son rapport :

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 09:05:27, on 08/11/2009
Platform: Windows XP SP3 (WinNT 5.01.2600)
MSIE: Internet Explorer v8.00 (8.00.6001.18702)
Boot mode: Normal

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\csrss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\RTHDCPL.EXE
C:\Program Files\LogMeIn\x86\LogMeInSystray.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\SuperCopier2\SuperCopier2.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Program Files\LogMeIn\x86\LMIGuardian.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\LogMeIn\x86\RaMaint.exe
C:\Program Files\LogMeIn\x86\LogMeIn.exe
C:\Program Files\LogMeIn\x86\LMIGuardian.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\alg.exe
C:\WINDOWS\Microsoft.NET\Framework\v3.0\WPF\PresentationFontCache.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\DOCUME~1\PROPRI~1\LOCALS~1\Temp\Div36A3.tmp\DivXInstaller.exe
C:\DOCUME~1\PROPRI~1\LOCALS~1\Temp\nsh36D2.tmp\DivXComponent.exe
C:\WINDOWS\system32\msiexec.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\WINDOWS\system32\wbem\wmiprvse.exe
C:\Documents and Settings\Propriétaire\Local Settings\Temporary Internet Files\Content.IE5\Q7OBEFYP\HiJackThis[1].exe
C:\DOCUME~1\PROPRI~1\LOCALS~1\Temp\nsh36D2.tmp\PxEngine\pxsetup.exe
C:\Documents and Settings\Propriétaire\Local Settings\Application Data\Mozilla\Firefox\Mozilla Firefox\updates\0\updater.exe
C:\WINDOWS\system32\pxhpinst.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.msn.com/fr-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 = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = "C:\Program Files\Outlook Express\msimn.exe"
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = *.local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files\Fichiers communs\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: IEVkbdBHO - {59273AB4-E7D3-40F9-A1A8-6FA9CCA1862C} - C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\ievkbd.dll
O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (no file)
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre6\bin\ssv.dll
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: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre6\bin\jp2ssv.dll
O2 - BHO: link filter bho - {E33CF602-D945-461A-83F0-819F76A199F8} - C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\klwtbbho.dll
O2 - BHO: JQSIEStartDetectorImpl - {E7E6F031-17CE-4C07-BC86-EABFE594F69C} - C:\Program Files\Java\jre6\lib\deploy\jqs\ie\jqs_plugin.dll
O4 - HKLM\..\Run: [RTHDCPL] RTHDCPL.EXE
O4 - HKLM\..\Run: [Alcmtr] ALCMTR.EXE
O4 - HKLM\..\Run: [LogMeIn GUI] "C:\Program Files\LogMeIn\x86\LogMeInSystray.exe"
O4 - HKLM\..\Run: [Malwarebytes Anti-Malware (reboot)] "C:\Program Files\Malwarebytes' Anti-Malware\mbam.exe" /runcleanupscript
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Program Files\Adobe\Reader 9.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [Adobe ARM] "C:\Program Files\Fichiers communs\Adobe\ARM\1.0\AdobeARM.exe"
O4 - HKLM\..\Run: [AVP] "C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\avp.exe"
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [SuperCopier2.exe] C:\Program Files\SuperCopier2\SuperCopier2.exe
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKCU\..\Run: [RGSC] E:\GTAIV\Rockstar Games Social Club\RGSCLauncher.exe /silent
O4 - HKCU\..\RunOnce: [WiseStubReboot] MSIEXEC /quiet SKIP_PPU_DRIVER_INSTALL=1 /I "C:\Program Files\Fichiers communs\Wise Installation Wizard\WISDD1865F0AD7340FBB23E1822E02396FF_9_09_0203.MSI" TRANSFORMS="C:\Program Files\Fichiers communs\Wise Installation Wizard\WISDD1865F0AD7340FBB23E1822E02396FF_9_09_0203.MST" WISE_SETUP_EXE_PATH="d:\driver\common\win2k_xp\PhysX_9.09.0203_SystemSoftware.exe"
O4 - HKUS\S-1-5-19\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\CTFMON.EXE (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-18\..\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: Ajouter à l'Anti-bannière - C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\ie_banner_deny.htm
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\OFFICE~1\OFFICE11\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre6\bin\jp2iexp.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre6\bin\jp2iexp.dll
O9 - Extra button: Clavier &virtuel - {4248FE82-7FCB-46AC-B270-339F08212110} - C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\klwtbbho.dll
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\OFFICE~1\OFFICE11\REFIEBAR.DLL
O9 - Extra button: Analyse des &liens - {CCF151D8-D089-449F-A5A4-D9909053F20F} - C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\klwtbbho.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: {E2883E8F-472F-4FB0-9522-AC9BF37916A7} - http://platformdl.adobe.com/NOS/getPlusPlus/1.6/gp.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{B5D81965-2995-4FA6-9B36-15DE1CF03B90}: NameServer = 208.67.222.222,208.67.220.220
O20 - AppInit_DLLs: C:\PROGRA~1\KASPER~1\KASPER~1\mzvkbd3.dll,C:\PROGRA~1\KASPER~1\KASPER~1\kloehk.dll
O23 - Service: Kaspersky Internet Security (AVP) - Kaspersky Lab - C:\Program Files\Kaspersky Lab\Kaspersky Internet Security 2010\avp.exe
O23 - Service: LogMeIn Maintenance Service (LMIMaint) - LogMeIn, Inc. - C:\Program Files\LogMeIn\x86\RaMaint.exe
O23 - Service: LogMeIn - LogMeIn, Inc. - C:\Program Files\LogMeIn\x86\LogMeIn.exe