Pc se coupe et repare tout seul...

salut
depuis 2 jours j ai un petit souci avec mon pc.
celui se coupe et redemarre tout seul assez souvent.
j ai fais un scan voici le resultat


ogfile of HijackThis v1.99.1
Scan saved at 17:00:25, on 27/05/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16441)

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\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Java\jre1.6.0_01\bin\jusched.exe
C:\Program Files\Network Associates\VirusScan\SHSTAT.EXE
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe
C:\Program Files\Network Associates\Common Framework\FrameworkService.exe
C:\Program Files\Network Associates\VirusScan\Mcshield.exe
C:\Program Files\Network Associates\VirusScan\VsTskMgr.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Program Files\Network Associates\VirusScan\SCAN32.EXE
C:\Documents and Settings\volos\Bureau\Nouveau dossier\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.google.fr
O2 - BHO: (no name) - {724d43a9-0d85-11d4-9908-00400523e39a} - C:\Program Files\Siber Systems\AI RoboForm\roboform.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)
O3 - Toolbar: &RoboForm - {724d43a0-0d85-11d4-9908-00400523e39a} - C:\Program Files\Siber Systems\AI RoboForm\roboform.dll
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_01\bin\jusched.exe"
O4 - HKLM\..\Run: [ShStatEXE] "C:\Program Files\Network Associates\VirusScan\SHSTAT.EXE" /STANDALONE
O4 - HKLM\..\Run: [KernelFaultCheck] %systemroot%\system32\dumprep 0 -k
O4 - HKLM\..\Run: [PCDAS] C:\Program Files\Defenza\pcd-as.exe /10003
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O8 - Extra context menu item: Barre RoboForm - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComShowToolbar.html
O8 - Extra context menu item: Enregistrer le formulaire - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComSavePass.html
O8 - Extra context menu item: Personnaliser le menu - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComCustomizeIEMenu.html
O8 - Extra context menu item: Remplir le formulaire - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComFillForms.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: Remplir - {320AF880-6646-11D3-ABEE-C5DBF3571F46} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComFillForms.html
O9 - Extra 'Tools' menuitem: Remplir le formulaire - {320AF880-6646-11D3-ABEE-C5DBF3571F46} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComFillForms.html
O9 - Extra button: Enregistrer - {320AF880-6646-11D3-ABEE-C5DBF3571F49} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComSavePass.html
O9 - Extra 'Tools' menuitem: Enregistrer le formulaire - {320AF880-6646-11D3-ABEE-C5DBF3571F49} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComSavePass.html
O9 - Extra button: Barre RoboForm - {724d43aa-0d85-11d4-9908-00400523e39a} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComShowToolbar.html
O9 - Extra 'Tools' menuitem: Barre RoboForm - {724d43aa-0d85-11d4-9908-00400523e39a} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComShowToolbar.html
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\OFFICE11\REFIEBAR.DLL
O16 - DPF: {4CCA4E80-9259-11D9-AC6E-444553544200} (FixController Control) - http://h30155.www3.hp.com/ediags/dd/install/HPInstallMgr_v01_5.cab
O16 - DPF: {AB86CE53-AC9F-449F-9399-D8ABCA09EC09} (Get_ActiveX Control) - https://h17000.www1.hp.com/ewfrf-JAVA/Secure/HPGetDownloadManager.ocx
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: WgaLogon - C:\WINDOWS\SYSTEM32\WgaLogon.dll
O23 - Service: Ati HotKey Poller - ATI Technologies Inc. - C:\WINDOWS\system32\Ati2evxx.exe
O23 - Service: AVG Anti-Spyware Guard - Anti-Malware Development a.s. - C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Fichiers communs\InstallShield\Driver\11\Intel 32\IDriverT.exe
O23 - Service: Service Framework McAfee (McAfeeFramework) - Network Associates, Inc. - C:\Program Files\Network Associates\Common Framework\FrameworkService.exe
O23 - Service: Network Associates McShield (McShield) - Network Associates, Inc. - C:\Program Files\Network Associates\VirusScan\Mcshield.exe
O23 - Service: Network Associates Task Manager (McTaskManager) - Network Associates, Inc. - C:\Program Files\Network Associates\VirusScan\VsTskMgr.exe

merci de me filer un coup de pouce.