SALUT,
Je connaiisais hijackthis mais je ne l'avais pas utiliser depuis longtemps...
ça donne ceci:

Logfile of HijackThis v1.99.1
Scan saved at 18:30:39, on 10/10/2005
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\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Sygate\SPF\smc.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\NVIDIA Corporation\NetworkAccessManager\Apache Group\Apache2\bin\apache.exe
C:\Program Files\NVIDIA Corporation\NetworkAccessManager\bin\nSvcIp.exe
C:\Program Files\NVIDIA Corporation\NetworkAccessManager\bin\nSvcLog.exe
C:\Program Files\Fichiers communs\Softwin\BitDefender Communicator\xcommsvr.exe
C:\Program Files\NVIDIA Corporation\NetworkAccessManager\bin\nSvcAppFlt.exe
C:\Program Files\Fichiers communs\Softwin\BitDefender Update Service\livesrv.exe
C:\Program Files\NVIDIA Corporation\NetworkAccessManager\Apache Group\Apache2\bin\apache.exe
C:\Program Files\Fichiers communs\Softwin\BitDefender Scan Server\bdss.exe
C:\Program Files\Softwin\BitDefender9\vsserv.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\progra~1\softwin\bitdef~1\bdswitch.exe
C:\progra~1\softwin\bitdef~1\bdmcon.exe
C:\progra~1\softwin\bitdef~1\bdnagent.exe
C:\Program Files\Softwin\BitDefender9\bdoesrv.exe
C:\WINDOWS\system32\wuauclt.exe
C:\WINDOWS\PCHealth\HelpCtr\Binaries\HelpHost.exe
C:\PROGRA~1\MOZILL~1\FIREFOX.EXE
D:\Programmes\maintenance\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://home.neuf.fr
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Local Page =
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O4 - HKLM\..\Run: [BDSwitchAgent] "C:\progra~1\softwin\bitdef~1\bdswitch.exe"
O4 - HKLM\..\Run: [SmcService] C:\PROGRA~1\Sygate\SPF\smc.exe -startgui
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [BDMCon] C:\progra~1\softwin\bitdef~1\bdmcon.exe
O4 - HKLM\..\Run: [BDOESRV] "C:\Program Files\Softwin\BitDefender9\bdoesrv.exe"
O4 - HKLM\..\Run: [BDNewsAgent] "C:\progra~1\softwin\bitdef~1\bdnagent.exe"
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\OFFICE11\EXCEL.EXE/3000
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\OFFICE11\REFIEBAR.DLL
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O10 - Unknown file in Winsock LSP: c:\windows\system32\nvappfilter.dll
O23 - Service: Ati HotKey Poller - ATI Technologies Inc. - C:\WINDOWS\system32\Ati2evxx.exe
O23 - Service: ATI Smart - Unknown owner - C:\WINDOWS\system32\ati2sgag.exe
O23 - Service: BitDefender Scan Server (bdss) - Unknown owner - C:\Program Files\Fichiers communs\Softwin\BitDefender Scan Server\bdss.exe" /service (file missing)
O23 - Service: ForceWare Intelligent Application Manager (IAM) - Unknown owner - C:\Program Files\NVIDIA Corporation\NetworkAccessManager\bin\nSvcAppFlt.exe
O23 - Service: Forceware Web Interface (ForcewareWebInterface) - Unknown owner - C:\Program Files\NVIDIA Corporation\NetworkAccessManager\Apache Group\Apache2\bin\apache.exe" -k runservice (file missing)
O23 - Service: BitDefender Desktop Update Service (LIVESRV) - Unknown owner - C:\Program Files\Fichiers communs\Softwin\BitDefender Update Service\livesrv.exe" /service (file missing)
O23 - Service: ForceWare IP service (nSvcIp) - NVIDIA - C:\Program Files\NVIDIA Corporation\NetworkAccessManager\bin\nSvcIp.exe
O23 - Service: ForceWare user log service (nSvcLog) - NVIDIA - C:\Program Files\NVIDIA Corporation\NetworkAccessManager\bin\nSvcLog.exe
O23 - Service: Sygate Personal Firewall (SmcService) - Sygate Technologies, Inc. - C:\Program Files\Sygate\SPF\smc.exe
O23 - Service: TuneUp WinStyler Theme Service (TUWinStylerThemeSvc) - TuneUp Software GmbH - C:\Program Files\TuneUp Utilities 2004\WinStylerThemeSvc.exe
O23 - Service: BitDefender Virus Shield (VSSERV) - Unknown owner - C:\Program Files\Softwin\BitDefender9\vsserv.exe" /service (file missing)
O23 - Service: BitDefender Communicator (XCOMM) - Unknown owner - C:\Program Files\Fichiers communs\Softwin\BitDefender Communicator\xcommsvr.exe" /service (file missing)

L'évaluation du log sur : http://www.hijackthis.de/fr est plutot bonne (pas d'inscription méchante).
Sinon je teste bitdefender pro.
Je pense avoir reglé le pb.

merci pour vos conseils