Infection ou pas ?

Bonjour,
pouvez vous m'aider a diagnostiquer mon PC ?
Je soupçonne une infection car j'ai un plantage avec écran bleu si je lance une analyse avec spyboat ou adaware .
Mon antivirus avast ( à jour ) ne détecte rien ( malgré l'analyse en mode sans échec avec désactivation de la restauration système ) .
les plantages sont causés par les fichiers suivants : le plus souvent par "win32k.sys , sinon "nv7mini.sys" ou "aswMon2.sys" .
Je vous soumet mon log de hijackthis avec l'espoir d'obtenir une solution .
Merci par avance pour votre aide .

Logfile of HijackThis v1.99.1
Scan saved at 20:04:51, on 08/01/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16574)

Running processes:
C:\WINDOWS\System32\smss.exe
C:\WINDOWS\system32\winlogon.exe
C:\WINDOWS\system32\services.exe
C:\WINDOWS\system32\savedump.exe
C:\WINDOWS\system32\lsass.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Windows Defender\MsMpEng.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Program Files\MainSoft\PC TimeWatch\PTWsvc.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Astase\UltraBackup\4.9\bin\thpassiveclientsvc.exe
C:\WINDOWS\system32\SearchIndexer.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\Program Files\Windows Defender\MSASCui.exe
C:\Program Files\Astase\UltraBackup\4.9\bin\thtrayagent.exe
C:\Program Files\Java\jre1.6.0_03\bin\jusched.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\Program Files\NVIDIA Corporation\NvMixer\NVMixerTray.exe
C:\WINDOWS\system32\RUNDLL32.EXE
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Astase\UltraBackup\4.9\bin\tbs.exe
C:\Program Files\MainSoft\PC TimeWatch\PctwTI.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Program Files\Hijackthis Version Française\hijackthis vf.exe
C:\WINDOWS\system32\SearchProtocolHost.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://www.google.fr/keyword/%s
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = http://www.google.fr/toolbar/ie8/sidebar.html
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.google.fr/?gws_rd=ssl
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.google.fr
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://www.google.fr/?gws_rd=ssl
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = https://www.google.fr/?gws_rd=ssl
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.google.fr/?gws_rd=ssl
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.google.fr/?gws_rd=ssl
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = http://www.google.fr/toolbar/ie8/sidebar.html
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://www.google.fr/keyword/%s
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Windows Ultimate Edition
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
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: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\SPYBOT~1\SDHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_03\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: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.1.615.5858\swg.dll
O3 - Toolbar: StylerToolBar - {D2F8F919-690B-4EA2-9FA7-A203D1E04F75} - C:\Program Files\styler\TB\StylerTB.dll
O4 - HKLM\..\Run: [_BackupService] "C:\Program Files\Astase\UltraBackup\4.9\bin\tbs.exe" -start
O4 - HKLM\..\Run: [Windows Defender] "C:\Program Files\Windows Defender\MSASCui.exe" -hide
O4 - HKLM\..\Run: [thnotify] "C:\Program Files\Astase\UltraBackup\4.9\bin\thtrayagent.exe" /start
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_03\bin\jusched.exe"
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NVMixerTray] "C:\Program Files\NVIDIA Corporation\NvMixer\NVMixerTray.exe"
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [KernelFaultCheck] %systemroot%\system32\dumprep 0 -k
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - Global Startup: PC TimeWatch Tray Icon.lnk = C:\Program Files\MainSoft\PC TimeWatch\PctwTI.exe
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~1\Office12\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_03\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_03\bin\ssv.dll
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~1\Office12\REFIEBAR.DLL
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - %windir%\Network Diagnostic\xpnetdiag.exe (file missing)
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - %windir%\Network Diagnostic\xpnetdiag.exe (file missing)
O11 - Options group: [INTERNATIONAL] International*
O11 - Options group: [TABS] Tabbed Browsing
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O15 - Trusted Zone:
O16 - DPF: {02BF25D5-8C17-4B23-BC80-D3488ABDDC6B} (QuickTime Object) - http://a1540.g.akamai.net/7/1540/52/20070711/qtinstall.info.apple.com/qtactivex/qtplugin.cab
O16 - DPF: {67DABFBF-D0AB-41FA-9C46-CC0F21721616} (DivXBrowserPlugin Object) - http://download.divx.com/player/DivXBrowserPlugin.cab
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsPAClient.cab56907.cab
O18 - Protocol: livecall - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\WI1F86~1\MESSEN~1\MSGRAP~1.DLL
O18 - Protocol: ms-help - {314111C7-A502-11D2-BBCA-00C04F8EC294} - C:\Program Files\Fichiers communs\Microsoft Shared\Help\hxds.dll
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\WI1F86~1\MESSEN~1\MSGRAP~1.DLL
O18 - Filter hijack: text/xml - {807563E5-5146-11D5-A672-00B0D022E945} - C:\PROGRA~1\FICHIE~1\MICROS~1\OFFICE12\MSOXMLMF.DLL
O20 - Winlogon Notify: LBTWlgn - c:\program files\fichiers communs\logishrd\bluetooth\LBTWlgn.dll
O20 - Winlogon Notify: WgaLogon - C:\WINDOWS\SYSTEM32\WgaLogon.dll
O21 - SSODL: WPDShServiceObj - {AAA288BA-9A4C-45B0-95D7-94D524869DB5} - C:\WINDOWS\system32\WPDShServiceObj.dll
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - Unknown owner - C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe" /service (file missing)
O23 - Service: avast! Web Scanner - Unknown owner - C:\Program Files\Alwil Software\Avast4\ashWebSv.exe" /service (file missing)
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Logitech Bluetooth Service (LBTServ) - Logitech, Inc. - C:\Program Files\Fichiers communs\Logishrd\Bluetooth\LBTServ.exe
O23 - Service: NBService - Nero AG - C:\Program Files\Nero\Nero 7\Nero BackItUp\NBService.exe
O23 - Service: NMIndexingService - Nero AG - C:\Program Files\Fichiers communs\Ahead\Lib\NMIndexingService.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: PCTimeWatch (PTWsvc) - MainSoft - C:\Program Files\MainSoft\PC TimeWatch\PTWsvc.exe
O23 - Service: ServiceLayer - Nokia. - C:\Program Files\PC Connectivity Solution\ServiceLayer.exe
O23 - Service: Astase ThalliumBackup Client Background Service (thpassivesvc) - Astase - C:\Program Files\Astase\UltraBackup\4.9\bin\thpassiveclientsvc.exe