PC qui s'arrête et qui redémarre tout seul.

Bonjour,
j'ai essayé de trouver réponse dans ce forum, mais sans succés.
Comme dit dans le titre, depuis un certain temps, mon PC reboot tout seul, plusieurs fois par jour.
Quand çà a commencé, j'ai de suite fait un anti-virus avec Avast, il m'a trouvé un cheval de troie dont je n'ai pas noté le nom.
Je pensais être tranquille, mais çà a continué.
J'ai donc cherché un peu sur ce forum, j'ai dépoussiéré mon PC (T° =30°C), j'ai fait un Memtest (pas de problème),j'ai fait un anti-virus en ligne (aucun virus).
Je vous joins un rapport Hijackthis, au cas ou çà parlerait à quelqu'un:

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 18:27:23, on 14/02/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
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\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Adobe\Photoshop Elements 3.0\PhotoshopElementsFileAgent.exe
C:\WINDOWS\system32\crypserv.exe
C:\WINDOWS\system32\mnmsrvc.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\WINDOWS\system32\rundll32.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\Program Files\Adobe\Photoshop Elements 3.0\PhotoshopElementsDeviceConnect.exe
C:\Program Files\Java\jre1.6.0_03\bin\jusched.exe
C:\Program Files\QuickTime\qttask.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\USB Product Driver v2\shwicon.exe
C:\WINDOWS\system32\XCSyncML.exe
C:\Program Files\Winamp\winampa.exe
C:\WINDOWS\VM_STI.EXE
C:\Program Files\Fichiers communs\Nokia\Tools\NclTray.exe
C:\Program Files\Fichiers communs\PCSuite\DataLayer\DataLayer.exe
C:\Program Files\Spamihilator\spamihilator.exe
C:\Program Files\Nokia\Nokia PC Suite 6\LaunchApplication.exe
C:\WINDOWS\taskmon.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Program Files\Shareaza\Shareaza.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\Program Files\Nokia\PC Suite for N-Gage QD\connmngmntbox.exe
C:\Program Files\Nokia\PC Suite for N-Gage QD\ectaskscheduler.exe
C:\Program Files\Philips\SPC 200NC PC Camera\TrayMin200.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\PROGRA~1\Nokia\PCSUIT~1\Elogerr.exe
C:\Program Files\Intuwave\Shared\mRouterRunTime\mRouterRuntime.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\Program Files\PC Connectivity Solution\ServiceLayer.exe
C:\WINDOWS\system32\wscntfy.exe
C:\PROGRA~1\Nokia\PCSUIT~1\BROADC~1.EXE
C:\PROGRA~1\Nokia\PCSUIT~1\SCRFS.exe
C:\WINDOWS\system32\WgaTray.exe
C:\Program Files\Outlook Express\msimn.exe
C:\PROGRA~1\MESSEN~1\Msmsgs.exe
C:\Program Files\Internet Explorer\IEXPLORE.EXE
C:\Program Files\Fichiers communs\Microsoft Shared\Windows Live\WLLoginProxy.exe
C:\Program Files\Trend Micro\HijackThis\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = https://www.bing.com/?FORM=TOOLBR&cc=fr&toHttps=1&redig=4527FFF1C12746FC9EDB535C75E80ECC
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?FORM=TOOLBR&cc=fr&toHttps=1&redig=4527FFF1C12746FC9EDB535C75E80ECC
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.free.fr/freebox/index.html
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = https://www.bing.com/?FORM=TOOLBR&cc=fr&toHttps=1&redig=4527FFF1C12746FC9EDB535C75E80ECC
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.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: (no name) - {84ED665E-25F2-9BC2-E8D2-59C4A849EF2D} - (no file)
O2 - BHO: Windows Live Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Fichiers communs\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O2 - BHO: Windows Live Toolbar Helper - {BDBD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Program Files\Windows Live Toolbar\msntb.dll
O3 - Toolbar: Windows Live Toolbar - {BDAD1DAD-C946-4A17-ADC1-64B5B4FF55D0} - C:\Program Files\Windows Live Toolbar\msntb.dll
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_03\bin\jusched.exe"
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [ShowIcon_MP3_USB Product Driver v2] "C:\Program Files\USB Product Driver v2\shwicon.exe" -t"MP3\USB Product Driver v2"
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [XCSyncML] C:\WINDOWS\system32\XCSyncML.exe
O4 - HKLM\..\Run: [WinampAgent] C:\Program Files\Winamp\winampa.exe
O4 - HKLM\..\Run: [BigDogPath] C:\WINDOWS\VM_STI.EXE Philips SPC 200NC PC Camera
O4 - HKLM\..\Run: [REGSHAVE] C:\Program Files\REGSHAVE\REGSHAVE.EXE /AUTORUN
O4 - HKLM\..\Run: [Nokia Tray Application] C:\Program Files\Fichiers communs\Nokia\Tools\NclTray.exe
O4 - HKLM\..\Run: [DataLayer] C:\Program Files\Fichiers communs\PCSuite\DataLayer\DataLayer.exe
O4 - HKLM\..\Run: [Spamihilator] "C:\Program Files\Spamihilator\spamihilator.exe"
O4 - HKLM\..\Run: [PCSuiteTrayApplication] C:\Program Files\Nokia\Nokia PC Suite 6\LaunchApplication.exe -startup
O4 - HKLM\..\Run: [Pense-bête] C:\Program Files\AXEL\Pense-bête\pensebet.exe
O4 - HKLM\..\Run: [taskmon] C:\WINDOWS\taskmon.exe
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\RunOnce: [!CleanupNetMeetingDispDriver] "C:\WINDOWS\system32\rundll32.exe" msconf.dll,CleanupNetMeetingDispDriver 0
O4 - HKCU\..\Run: [Shareaza] "C:\Program Files\Shareaza\Shareaza.exe" -tray
O4 - HKCU\..\Run: [Heart Mags] C:\DOCUME~1\JACQUO~1\APPLIC~1\GREATS~1\Mode Knob.exe
O4 - HKCU\..\Run: [EssentialPIM] "C:\Program Files\EssentialPIM\EssentialPIM.exe" /autorun
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.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')
O4 - Global Startup: Adobe Gamma Loader.lnk = C:\Program Files\Fichiers communs\Adobe\Calibration\Adobe Gamma Loader.exe
O4 - Global Startup: Lancement rapide d'Adobe Reader.lnk = C:\Program Files\Adobe\Acrobat 7.0\Reader\reader_sl.exe
O4 - Global Startup: PCSuiteForNokiaN-Gage QD Detect.lnk = ?
O4 - Global Startup: PCSuiteForNokiaN-Gage QD TS.lnk = ?
O4 - Global Startup: Pense-bête.lnk = C:\Program Files\Broderbund\PrintMaster\PMREMIND.EXE
O4 - Global Startup: TrayMin300.exe.lnk = ?
O8 - Extra context menu item: &Windows Live Search - res://C:\Program Files\Windows Live Toolbar\msntb.dll/search.htm
O8 - Extra context menu item: Add to Windows &Live Favorites - https://onedrive.live.com/?id=favorites
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\OFFICE11\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: Run WinHTTrack - {36ECAF82-3300-8F84-092E-AFF36D6C7040} - C:\Program Files\WinHTTrack\WinHTTrackIEBar.dll
O9 - Extra 'Tools' menuitem: Launch WinHTTrack - {36ECAF82-3300-8F84-092E-AFF36D6C7040} - C:\Program Files\WinHTTrack\WinHTTrackIEBar.dll
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\OFFICE11\REFIEBAR.DLL
O9 - Extra button: @C:\Program Files\Messenger\Msgslang.dll,-61144 - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O9 - Extra 'Tools' menuitem: @C:\Program Files\Messenger\Msgslang.dll,-61144 - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\msmsgs.exe
O12 - Plugin for .spop: C:\Program Files\Internet Explorer\Plugins\NPDocBox.dll
O16 - DPF: {1F2F4C9E-6F09-47BC-970D-3C54734667FE} - https://support.norton.com/sp/en/us/home/current/info
O16 - DPF: {867E13F2-7F31-44FB-AC97-CD38E0DC46EF} (HardwareDetection Control) - http://charon777.free.fr/plugins/hardwaredetection_2_0_4_12.cab
O16 - DPF: {9A9307A0-7DA4-4DAF-B042-5009F29E09E1} (ActiveScan Installer Class) - http://acs.pandasoftware.com/activescan/as5free/asinst.cab
O16 - DPF: {CE28D5D2-60CF-4C7D-9FE8-0F47A3308078} (ActiveDataInfo Class) - https://support.norton.com/sp/en/us/home/current/info
O20 - AppInit_DLLs: 14.dll
O23 - Service: Adobe Active File Monitor (AdobeActiveFileMonitor) - Unknown owner - C:\Program Files\Adobe\Photoshop Elements 3.0\PhotoshopElementsFileAgent.exe
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: Automatic LiveUpdate Scheduler - Unknown owner - C:\Program Files\Symantec\LiveUpdate\ALUSchedulerSvc.exe (file missing)
O23 - Service: avast! Antivirus - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
O23 - Service: avast! Web Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
O23 - Service: Boonty Games - BOONTY - C:\Program Files\Fichiers communs\BOONTY Shared\Service\Boonty.exe
O23 - Service: Crypkey License - Kenonic Controls Ltd. - C:\WINDOWS\SYSTEM32\crypserv.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Fichiers communs\InstallShield\Driver\1150\Intel 32\IDriverT.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: Photoshop Elements Device Connect (PhotoshopElementsDeviceConnect) - Unknown owner - C:\Program Files\Adobe\Photoshop Elements 3.0\PhotoshopElementsDeviceConnect.exe
O23 - Service: ServiceLayer - Nokia. - C:\Program Files\PC Connectivity Solution\ServiceLayer.exe
O23 - Service: Windows Live Setup Service (WLSetupSvc) - Unknown owner - C:\Program Files\Windows Live\installer\WLSetupSvc.exe