mon ordi reboot tout seul quand j'arrive au poste de travail

Bonjour à tous,
mon pc reboot tout seul des que j'arrive au poste de travail(donc environ 1 min) et cela seulement depuis cette après midi ,j'ai utilise les logs(tine up utilities et je crois que j'ai fait une fausse manip en voulant defragmenter le pc)je n'avais jamais fait ca auparavant . apeès la defragmentation , on ma demande de rebooté le pc mais j'ai repoussé a plus tard. puis j'ai installer avast pour remplacer kaspersky qui prenait trop de bande passante et j'ai du redemarre le pc pour que les modif soient pris en compte.puis la c'est lde drame , ca ne cesse de rebooté quand j'arrive au poste de travail. c'est la premiere fois que ca arrive et depuis il ne fait que ca .
mais en mode sans echec ca marche impec , je voudrais donc avoir d'ou vient ce probleme.
aidez moi svp

voici le rapport avec hijackthis


Logfile of HijackThis v1.99.1
Scan saved at 21:09:58, on 02/07/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)

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:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\WgaTray.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe
C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\avgas.exe
C:\Program Files\WinRAR\WinRAR.exe
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\Rar$EX00.531\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://www.google.fr
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://www.google.fr
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://www.google.fr
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://www.google.fr
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.google.fr
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant = http://www.google.fr/ie
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://www.google.fr/keyword/%s
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 5.0\Reader\ActiveX\AcroIEHelper.ocx
O2 - BHO: (no name) - {53707962-6F74-2D53-2644-206D7942484F} - C:\PROGRA~1\Spybot\SDHelper.dll
O2 - BHO: DealioBHO Class - {6A87B991-A31F-4130-AE72-6D0C294BF082} - C:\Program Files\Dealio\kb105\Dealio.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_01\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (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
O3 - Toolbar: Dealio - {E67C74F4-A00A-4F2C-9FEC-FD9DC004A67F} - C:\Program Files\Dealio\kb105\Dealio.dll
O4 - HKLM\..\Run: [HP Component Manager] "C:\Program Files\HP\hpcoretech\hpcmpmgr.exe"
O4 - HKLM\..\Run: [HP Software Update] C:\Program Files\HP\HP Software Update\HPWuSchd2.exe
O4 - HKLM\..\Run: [au] C:\Program Files\Dealio\DealioAU.exe
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [kav] "C:\Program Files\Kaspersky Lab\Kaspersky Anti-Virus 6.0\avp.exe"
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [AlcxMonitor] ALCXMNTR.EXE
O4 - HKLM\..\Run: [AGRSMMSG] AGRSMMSG.exe
O4 - HKLM\..\Run: [!AVG Anti-Spyware] "C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\avgas.exe" /minimized
O4 - HKCU\..\Run: [SpySweeper] "C:\Program Files\SpySweeper\SpySweeper.exe" /0
O4 - HKCU\..\Run: [eMuleAutoStart] C:\Program Files\eMule\emule.exe -AutoStart
O8 - Extra context menu item: Compare Prices with &Dealio - C:\Program Files\Dealio\kb105\res\DealioSearch.html
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_01\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_01\bin\ssv.dll
O9 - Extra button: Web Anti-Virus - {1F460357-8A94-4D71-9CA3-AA4ACF32ED8E} - C:\Program Files\Kaspersky Lab\Kaspersky Anti-Virus 6.0\scieplugin.dll
O9 - Extra button: Dealio - {E908B145-C847-4e85-B315-07E2E70DECF8} - C:\Program Files\Dealio\kb105\Dealio.dll
O9 - Extra button: Internet Cleaner - {45819E58-6E84-4A5D-BD65-A706981E5BE8} - C:\Program Files\Internet Cleaner\ICleaner.exe (HKCU)
O9 - Extra 'Tools' menuitem: Internet Cleaner - {45819E58-6E84-4A5D-BD65-A706981E5BE8} - C:\Program Files\Internet Cleaner\ICleaner.exe (HKCU)
O16 - DPF: {14B87622-7E19-4EA8-93B3-97215F77A6BC} (MessengerStatsClient Class) - http://messenger.zone.msn.com/bina [...] b31267.cab
O16 - DPF: {20A60F0D-9AFA-4515-A0FD-83BD84642501} (Checkers Class) - http://messenger.zone.msn.com/bina [...] b56986.cab
O16 - DPF: {5D6F45B3-9043-443D-A792-115447494D24} (UnoCtrl Class) - http://messenger.zone.msn.com/FR-F [...] E_UNO1.cab
O16 - DPF: {8E0D4DE5-3180-4024-A327-4DFAD1796A8D} (MessengerStatsClient Class) - http://messenger.zone.msn.com/bina [...] b31267.cab
O16 - DPF: {B8BE5E93-A60C-4D26-A2DC-220313175592} (MSN Games - Installer) - http://messenger.zone.msn.com/bina [...] b56649.cab
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/bina [...] b56907.cab
O16 - DPF: {F6BF0D00-0B2A-4A75-BF7B-F385591623AF} (Solitaire Showdown Class) - http://messenger.zone.msn.com/bina [...] b31267.cab
O18 - Protocol: livecall - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\MSNMES~1\MSGRAP~1.DLL
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\MSNMES~1\MSGRAP~1.DLL
O20 - Winlogon Notify: klogon - C:\WINDOWS\system32\klogon.dll
O20 - Winlogon Notify: WgaLogon - C:\WINDOWS\SYSTEM32\WgaLogon.dll
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - Unknown owner - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - Unknown owner - 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: AVG Anti-Spyware Guard - GRISOFT s.r.o. - C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe
O23 - Service: Kaspersky Anti-Virus 6.0 (AVP) - Unknown owner - C:\Program Files\Kaspersky Lab\Kaspersky Anti-Virus 6.0\avp.exe" -r (file missing)
O23 - Service: Creative Service for CDROM Access - Creative Technology Ltd - C:\WINDOWS\system32\CTsvcCDA.EXE
O23 - Service: Diskeeper - Executive Software International, Inc. - C:\Program Files\Executive Software\Diskeeper\DkService.exe
O23 - Service: GhostStartService - Symantec Corporation - C:\PROGRA~1\Symantec\NORTON~1\GHOSTS~2.EXE
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Fichiers communs\InstallShield\Driver\1050\Intel 32\IDriverT.exe
O23 - Service: MSCSPTISRV - Sony Corporation - C:\Program Files\Fichiers communs\Sony Shared\AVLib\MSCSPTISRV.exe
O23 - Service: NBService - Nero AG - C:\Program Files\Nero\Nero 7\Nero BackItUp\NBService.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: PACSPTISVR - Sony Corporation - C:\Program Files\Fichiers communs\Sony Shared\AVLib\PACSPTISVR.exe
O23 - Service: Pml Driver HPZ12 - HP - C:\WINDOWS\system32\HPZipm12.exe
O23 - Service: Sony SCSI Helper Service - Sony Corporation - C:\Program Files\Fichiers communs\Sony Shared\Fsk\SonySCSIHelperService.exe
O23 - Service: Sony SPTI Service (SPTISRV) - Sony Corporation - C:\Program Files\Fichiers communs\Sony Shared\AVLib\SPTISRV.exe