Ralentissement PC... Virus ?

Bonjour,
Depuis quelques jours, je suis confronté à un problème, mon pc rame. Attention, ce n'est pas dans la navigation Windows, ni sur internet et tout, mais sur les jeux. Il y a une semaine encore je jouais en qualité élevée sur presque tous mes jeux, et tout était fluide, beau... Et un soir, je rentre chez moi j'allume WoW (20 minutes avant j'étais dessus en qualité élevée) et la ca lague énormément, c'était injouable.
J'ai pensé à ma connexion, je reboote la box, pareil. je pense ensuite a rebooter le pc, pareil. Je défragmente, un coup de CCleaner, scan Avast minutieux, et tout redeviens normal. 2 jours après, ca recommence. Sur le net on me dis de faire une analyse malware, je la fait, et tout redeviens encore normal. Mais la, hier soir, ca recommence. Ce matin un collègue m'a tout mis à jour (CG, pross,...) optimisé avec le défragmenteur, controllé les processus et tout. Rien à faire.

Voici mon rapport hijackthis :

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 11:19:00, on 08/12/2010
Platform: Unknown Windows (WinNT 6.01.3504)
MSIE: Internet Explorer v9.00 (9.00.7930.16406)
Boot mode: Normal

Running processes:
C:\Program Files (x86)\Mozilla Firefox\firefox.exe
C:\Program Files (x86)\Mozilla Firefox\plugin-container.exe
C:\Users\ALEXANDRE\Downloads\HiJackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://homepage.packardbell.com/...
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://homepage.packardbell.com/rdr.aspx?b=ACPW&l=040c&m=easynote_lm86&r=2736091052b6l0420z1i5f4591a267
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://homepage.packardbell.com/...
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://homepage.packardbell.com/rdr.aspx?b=ACPW&l=040c&m=easynote_lm86&r=2736091052b6l0420z1i5f4591a267
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page = C:\Windows\SysWOW64\blank.htm
R1 - HKCU\Software\Microsoft\Windows\CurrentVersion\Internet Settings,ProxyOverride = *.local
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
F2 - REG:system.ini: UserInit=userinit.exe,
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files (x86)\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: Search Helper - {6EBF7485-159F-4bff-A14F-B9E3AAC4465B} - C:\Program Files (x86)\Microsoft\Search Enhancement Pack\Search Helper\SEPsearchhelperie.dll
O2 - BHO: Groove GFS Browser Helper - {72853161-30C5-4D22-B7F9-0BBC1D38A37E} - C:\PROGRA~2\MICROS~2\Office14\GROOVEEX.DLL
O2 - BHO: Programme d'aide de l'Assistant de connexion Windows Live ID - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files (x86)\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Windows Live Messenger Companion Helper - {9FDDE16B-836F-4806-AB1F-1455CBEFF289} - C:\Program Files (x86)\Windows Live\Companion\companioncore.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - C:\Program Files (x86)\Google\Google Toolbar\GoogleToolbar_32.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files (x86)\Google\GoogleToolbarNotifier\5.6.5805.1910\swg.dll
O2 - BHO: URLRedirectionBHO - {B4F3A835-0E21-4959-BA22-42B3008E02FF} - C:\PROGRA~2\MICROS~2\Office14\URLREDIR.DLL
O2 - BHO: Bing Bar BHO - {d2ce3e00-f94a-4740-988e-03dc2f38c34f} - C:\Program Files (x86)\MSN Toolbar\Platform\6.0.2156.0\npwinext.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files (x86)\Java\jre6\bin\jp2ssv.dll
O3 - Toolbar: @C:\Program Files (x86)\MSN Toolbar\Platform\6.0.2156.0\npwinext.dll,-100 - {8dcb7100-df86-4384-8842-8fa844297b3f} - C:\Program Files (x86)\MSN Toolbar\Platform\6.0.2156.0\npwinext.dll
O3 - Toolbar: Google Toolbar - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - C:\Program Files (x86)\Google\Google Toolbar\GoogleToolbar_32.dll
O4 - HKLM\..\Run: [avast5] "C:\Program Files\Alwil Software\Avast5\avastUI.exe" /nogui
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-19\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /autoRun (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-20\..\RunOnce: [mctadmin] C:\Windows\System32\mctadmin.exe (User 'SERVICE RÉSEAU')
O8 - Extra context menu item: &Envoyer à OneNote - res://C:\PROGRA~1\MICROS~2\Office14\ONBttnIE.dll/105
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office14\EXCEL.EXE/3000
O8 - Extra context menu item: Google Sidewiki... - res://C:\Program Files (x86)\Google\Google Toolbar\Component\GoogleToolbarDynamic_mui_en_950DF09FAB501E03.dll/cmsidewiki.html
O9 - Extra button: @C:\Program Files (x86)\Windows Live\Companion\companionlang.dll,-600 - {0000036B-C524-4050-81A0-243669A86B9F} - C:\Program Files (x86)\Windows Live\Companion\companioncore.dll
O9 - Extra button: @C:\Program Files (x86)\Windows Live\Writer\WindowsLiveWriterShortcuts.dll,-1004 - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Program Files (x86)\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra 'Tools' menuitem: @C:\Program Files (x86)\Windows Live\Writer\WindowsLiveWriterShortcuts.dll,-1003 - {219C3416-8CB2-491a-A3C7-D9FCDDC9D600} - C:\Program Files (x86)\Windows Live\Writer\WriterBrowserExtension.dll
O9 - Extra button: Envoyer à OneNote - {2670000A-7350-4f3c-8081-5663EE0C6C49} - C:\Program Files (x86)\Microsoft Office\Office14\ONBttnIE.dll
O9 - Extra 'Tools' menuitem: &Envoyer à OneNote - {2670000A-7350-4f3c-8081-5663EE0C6C49} - C:\Program Files (x86)\Microsoft Office\Office14\ONBttnIE.dll
O9 - Extra button: Notes &liées OneNote - {789FE86F-6FC4-46A1-9849-EDE0DB0C95CA} - C:\Program Files (x86)\Microsoft Office\Office14\ONBttnIELinkedNotes.dll
O9 - Extra 'Tools' menuitem: Notes &liées OneNote - {789FE86F-6FC4-46A1-9849-EDE0DB0C95CA} - C:\Program Files (x86)\Microsoft Office\Office14\ONBttnIELinkedNotes.dll
O10 - Unknown file in Winsock LSP: c:\program files (x86)\common files\microsoft shared\windows live\wlidnsp.dll
O10 - Unknown file in Winsock LSP: c:\program files (x86)\common files\microsoft shared\windows live\wlidnsp.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\prxernsp.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\prxerdrv.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\prxerdrv.dll
O11 - Options group: [ACCELERATED_GRAPHICS] Accelerated graphics
O13 - Gopher Prefix:
O18 - Protocol: skype4com - {FFC8B962-9B40-4DFF-9458-1830C7DD7F5D} - C:\PROGRA~2\COMMON~1\Skype\SKYPE4~1.DLL
O18 - Protocol: wlpg - {E43EF6CD-A37A-4A9B-9E6F-83F89B8E6324} - C:\Program Files (x86)\Windows Live\Photo Gallery\AlbumDownloadProtocolHandler.dll
O18 - Filter hijack: text/xml - {807573E5-5146-11D5-A672-00B0D022E945} - C:\Program Files (x86)\Common Files\Microsoft Shared\OFFICE14\MSOXMLMF.DLL
O23 - Service: Adobe LM Service - Unknown owner - C:\Program Files (x86)\Common Files\Adobe Systems Shared\Service\Adobelmsvc.exe
O23 - Service: Adobe Active File Monitor V7 (AdobeActiveFileMonitor7.0) - Adobe Systems Incorporated - c:\Program Files (x86)\Adobe\Photoshop Elements 7.0\PhotoshopElementsFileAgent.exe
O23 - Service: @%SystemRoot%\system32\Alg.exe,-112 (ALG) - Unknown owner - C:\Windows\System32\alg.exe (file missing)
O23 - Service: AMD External Events Utility - Unknown owner - C:\Windows\system32\atiesrxx.exe (file missing)
O23 - Service: Apple Mobile Device - Apple Inc. - C:\Program Files (x86)\Common Files\Apple\Mobile Device Support\AppleMobileDeviceService.exe
O23 - Service: avast! Antivirus - AVAST Software - C:\Program Files\Alwil Software\Avast5\AvastSvc.exe
O23 - Service: avast! Mail Scanner - AVAST Software - C:\Program Files\Alwil Software\Avast5\AvastSvc.exe
O23 - Service: avast! Web Scanner - AVAST Software - C:\Program Files\Alwil Software\Avast5\AvastSvc.exe
O23 - Service: Service Bonjour (Bonjour Service) - Apple Inc. - C:\Program Files (x86)\Bonjour\mDNSResponder.exe
O23 - Service: Device Error Recovery Service (dgdersvc) - Devguru Co., Ltd. - C:\Windows\SysWOW64\dgdersvc.exe
O23 - Service: Dritek WMI Service (DsiWMIService) - Dritek System Inc. - C:\Program Files (x86)\Launch Manager\dsiwmis.exe
O23 - Service: @%SystemRoot%\system32\efssvc.dll,-100 (EFS) - Unknown owner - C:\Windows\System32\lsass.exe (file missing)
O23 - Service: Acer ePower Service (ePowerSvc) - Acer Incorporated - C:\Program Files\Packard Bell\Packard Bell Power Management\ePowerSvc.exe
O23 - Service: @%systemroot%\system32\fxsresm.dll,-118 (Fax) - Unknown owner - C:\Windows\system32\fxssvc.exe (file missing)
O23 - Service: FLEXnet Licensing Service - Macrovision Europe Ltd. - C:\Program Files (x86)\Common Files\Macrovision Shared\FLEXnet Publisher\FNPLicensingService.exe
O23 - Service: GameConsoleService - WildTangent, Inc. - C:\Program Files (x86)\Packard Bell Games\Packard Bell Game Console\GameConsoleService.exe
O23 - Service: GRegService (Greg_Service) - Acer Incorporated - C:\Program Files (x86)\Packard Bell\Registration\GregHSRW.exe
O23 - Service: Service Google Update (gupdate) (gupdate) - Google Inc. - C:\Program Files (x86)\Google\Update\GoogleUpdate.exe
O23 - Service: Google Software Updater (gusvc) - Google - C:\Program Files (x86)\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Intel(R) Rapid Storage Technology (IAStorDataMgrSvc) - Intel Corporation - C:\Program Files (x86)\Intel\Intel(R) Rapid Storage Technology\IAStorDataMgrSvc.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files (x86)\Common Files\InstallShield\Driver\11\Intel 32\IDriverT.exe
O23 - Service: Service de l'iPod (iPod Service) - Apple Inc. - C:\Program Files\iPod\bin\iPodService.exe
O23 - Service: @keyiso.dll,-100 (KeyIso) - Unknown owner - C:\Windows\system32\lsass.exe (file missing)
O23 - Service: Intel(R) Management and Security Application Local Management Service (LMS) - Intel Corporation - C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\LMS\LMS.exe
O23 - Service: Ma-Config Service (maconfservice) - CybelSoft - C:\Program Files (x86)\ma-config.com\maconfservice.exe
O23 - Service: @comres.dll,-2797 (MSDTC) - Unknown owner - C:\Windows\System32\msdtc.exe (file missing)
O23 - Service: @C:\Program Files (x86)\Nero\Update\NASvc.exe,-200 (NAUpdate) - Nero AG - C:\Program Files (x86)\Nero\Update\NASvc.exe
O23 - Service: Nero BackItUp Scheduler 4.0 - Nero AG - c:\Program Files (x86)\Common Files\Nero\Nero BackItUp 4\NBService.exe
O23 - Service: @%SystemRoot%\System32\netlogon.dll,-102 (Netlogon) - Unknown owner - C:\Windows\system32\lsass.exe (file missing)
O23 - Service: NTI IScheduleSvc - NewTech Infosystems, Inc. - C:\Program Files (x86)\NewTech Infosystems\Packard Bell MyBackup\IScheduleSvc.exe
O23 - Service: PnkBstrA - Unknown owner - C:\Windows\system32\PnkBstrA.exe
O23 - Service: PnkBstrB - Unknown owner - C:\Windows\system32\PnkBstrB.exe
O23 - Service: @%systemroot%\system32\psbase.dll,-300 (ProtectedStorage) - Unknown owner - C:\Windows\system32\lsass.exe (file missing)
O23 - Service: @%systemroot%\system32\Locator.exe,-2 (RpcLocator) - Unknown owner - C:\Windows\system32\locator.exe (file missing)
O23 - Service: @%SystemRoot%\system32\samsrv.dll,-1 (SamSs) - Unknown owner - C:\Windows\system32\lsass.exe (file missing)
O23 - Service: @%SystemRoot%\system32\snmptrap.exe,-3 (SNMPTRAP) - Unknown owner - C:\Windows\System32\snmptrap.exe (file missing)
O23 - Service: @%systemroot%\system32\spoolsv.exe,-1 (Spooler) - Unknown owner - C:\Windows\System32\spoolsv.exe (file missing)
O23 - Service: @%SystemRoot%\system32\sppsvc.exe,-101 (sppsvc) - Unknown owner - C:\Windows\system32\sppsvc.exe (file missing)
O23 - Service: Steam Client Service - Valve Corporation - C:\Program Files (x86)\Common Files\Steam\SteamService.exe
O23 - Service: TurboBoost - Intel(R) Corporation - C:\Program Files\Intel\TurboBoost\TurboBoost.exe
O23 - Service: @%SystemRoot%\system32\ui0detect.exe,-101 (UI0Detect) - Unknown owner - C:\Windows\system32\UI0Detect.exe (file missing)
O23 - Service: Intel(R) Management & Security Application User Notification Service (UNS) - Intel Corporation - C:\Program Files (x86)\Intel\Intel(R) Management Engine Components\UNS\UNS.exe
O23 - Service: Updater Service - Acer - C:\Program Files\Packard Bell\Packard Bell Updater\UpdaterService.exe
O23 - Service: @%SystemRoot%\system32\vaultsvc.dll,-1003 (VaultSvc) - Unknown owner - C:\Windows\system32\lsass.exe (file missing)
O23 - Service: @%SystemRoot%\system32\vds.exe,-100 (vds) - Unknown owner - C:\Windows\System32\vds.exe (file missing)
O23 - Service: @%systemroot%\system32\vssvc.exe,-102 (VSS) - Unknown owner - C:\Windows\system32\vssvc.exe (file missing)
O23 - Service: @%SystemRoot%\system32\Wat\WatUX.exe,-601 (WatAdminSvc) - Unknown owner - C:\Windows\system32\Wat\WatAdminSvc.exe (file missing)
O23 - Service: @%systemroot%\system32\wbengine.exe,-104 (wbengine) - Unknown owner - C:\Windows\system32\wbengine.exe (file missing)
O23 - Service: @%Systemroot%\system32\wbem\wmiapsrv.exe,-110 (wmiApSrv) - Unknown owner - C:\Windows\system32\wbem\WmiApSrv.exe (file missing)
O23 - Service: @%PROGRAMFILES%\Windows Media Player\wmpnetwk.exe,-101 (WMPNetworkSvc) - Unknown owner - C:\Program Files (x86)\Windows Media Player\wmpnetwk.exe (file missing)