Reboot intempestif

Bonjour a tous

Je me permet de vous demander votre aide car lorsque je lance internet explorer, le pc plante au bout de 2 mn et reboote tout seul.

j'ai fait toutes les recherche en mode sans echec avec:
spyboot
ad-aware
regystri cleaner
cleanup
a-squared
avast antivirus

mais rien n'y fait.

voici mon dernier log:

Logfile of HijackThis v1.99.1
Scan saved at 20:01:07, on 24/09/2005
Platform: Windows XP (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 (6.00.2600.0000)

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\spoolsv.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\Program Files\Analog Devices\SoundMAX\SMAgent.exe
C:\WINDOWS\system32\ZoneLabs\vsmon.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\Program Files\ATI Technologies\ATI Control Panel\atiptaxx.exe
C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\Program Files\Fichiers communs\Real\Update_OB\realsched.exe
C:\WINDOWS\System32\MMTray.exe
C:\WINDOWS\System32\MMTray2k.exe
C:\WINDOWS\System32\MMTrayLSI.exe
C:\Program Files\QuickTime\qttask.exe
C:\Program Files\Analog Devices\SoundMAX\SMax4PNP.exe
C:\Program Files\Analog Devices\SoundMAX\Smax4.exe
C:\WINDOWS\System32\ctfmon.exe
C:\Program Files\Messenger\msmsgs.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\System32\wuauclt.exe
C:\WINDOWS\System32\wuauclt.exe
C:\WINDOWS\System32\taskmgr.exe
C:\WINDOWS\explorer.exe
C:\Documents and Settings\lolo\Bureau\antivirus\HijackThis.exe

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~1\SDHelper.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINDOWS\System32\msdxm.ocx
O3 - Toolbar: Easy-WebPrint - {327C2873-E90D-4c37-AA9D-10AC9BABA46C} - C:\Program Files\Canon\Easy-WebPrint\Toolband.dll
O4 - HKLM\..\Run: [ATIPTA] C:\Program Files\ATI Technologies\ATI Control Panel\atiptaxx.exe
O4 - HKLM\..\Run: [Zone Labs Client] "C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe"
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [TkBellExe] "C:\Program Files\Fichiers communs\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [MMTray] MMTray.exe
O4 - HKLM\..\Run: [MMTray2K] MMTray2k.exe
O4 - HKLM\..\Run: [MMTrayLSI] MMTrayLSI.exe
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [Tweak UI] RUNDLL32.EXE TWEAKUI.CPL,TweakMeUp
O4 - HKLM\..\Run: [SoundMAXPnP] C:\Program Files\Analog Devices\SoundMAX\SMax4PNP.exe
O4 - HKLM\..\Run: [SoundMAX] "C:\Program Files\Analog Devices\SoundMAX\Smax4.exe" /tray
O4 - HKLM\..\Run: [Easy-PrintToolBox] C:\Program Files\Canon\Easy-PrintToolBox\BJPSMAIN.EXE /logon
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\System32\ctfmon.exe
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office\OSA9.EXE
O8 - Extra context menu item: Easy-WebPrint Ajouter à la liste d'impressions - res://C:\Program Files\Canon\Easy-WebPrint\Resource.dll/RC_AddToList.html
O8 - Extra context menu item: Easy-WebPrint Impression rapide - res://C:\Program Files\Canon\Easy-WebPrint\Resource.dll/RC_HSPrint.html
O8 - Extra context menu item: Easy-WebPrint Imprimer - res://C:\Program Files\Canon\Easy-WebPrint\Resource.dll/RC_Print.html
O8 - Extra context menu item: Easy-WebPrint Prévisualiser - res://C:\Program Files\Canon\Easy-WebPrint\Resource.dll/RC_Preview.html
O9 - Extra button: Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\MSMSGS.EXE
O9 - Extra 'Tools' menuitem: Windows Messenger - {FB5F1910-F110-11d2-BB9E-00C04F795683} - C:\Program Files\Messenger\MSMSGS.EXE
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - Unknown owner - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: Ati HotKey Poller - Unknown owner - C:\WINDOWS\System32\Ati2evxx.exe
O23 - Service: ATI Smart - Unknown owner - C:\WINDOWS\system32\ati2sgag.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: SoundMAX Agent Service (SoundMAX Agent Service (default)) - Analog Devices, Inc. - C:\Program Files\Analog Devices\SoundMAX\SMAgent.exe
O23 - Service: TrueVector Internet Monitor (vsmon) - Zone Labs Inc. - C:\WINDOWS\system32\ZoneLabs\vsmon.exe

merci de votre aide