Voici le log :

Logfile of HijackThis v1.99.1
Scan saved at 19:02:34, on 05/01/2007
Platform: Windows XP (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP1 (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\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\Explorer.EXE
C:\PROGRA~1\Wanadoo\CnxMon.exe
C:\PROGRA~1\Wanadoo\TaskbarIcon.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\System32\ctfmon.exe
C:\Program Files\SAGEM\SAGEM F@st 800-840\dslmon.exe
C:\Program Files\SpywareGuard\sgmain.exe
C:\Program Files\SpywareGuard\sgbhp.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe
C:\WINDOWS\system32\ZoneLabs\vsmon.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\PROGRA~1\Wanadoo\EspaceWanadoo.exe
C:\PROGRA~1\Wanadoo\ComComp.exe
C:\PROGRA~1\Wanadoo\Watch.exe
C:\Program Files\Mozilla Thunderbird\thunderbird.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Documents and Settings\Bureau\Bureau\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://www.wanadoo.fr
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Wanadoo
R3 - URLSearchHook: Search Class - {08C06D61-F1F3-4799-86F8-BE1A89362C85} - C:\PROGRA~1\Wanadoo\SEARCH~1.DLL
O2 - BHO: SpywareGuard Download Protection - {4A368E80-174F-4872-96B5-0B27DDD11DB2} - C:\Program Files\SpywareGuard\dlprotect.dll
O4 - HKLM\..\Run: [WooCnxMon] C:\PROGRA~1\Wanadoo\CnxMon.exe
O4 - HKLM\..\Run: [WOOTASKBARICON] C:\PROGRA~1\Wanadoo\TaskbarIcon.exe
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [Zone Labs Client] "C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe"
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\System32\ctfmon.exe
O4 - Startup: SpywareGuard.lnk = C:\Program Files\SpywareGuard\sgmain.exe
O4 - Global Startup: DSLMON.lnk = C:\Program Files\SAGEM\SAGEM F@st 800-840\dslmon.exe
O17 - HKLM\System\CCS\Services\Tcpip\..\{4E84B670-6633-4685-9EEB-63CBC09F99ED}: NameServer = 80.10.246.130 80.10.246.3
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: lxcg_device - - C:\WINDOWS\System32\lxcgcoms.exe
O23 - Service: TrueVector Internet Monitor (vsmon) - Zone Labs, LLC - C:\WINDOWS\system32\ZoneLabs\vsmon.exe


... et merci de te pencher sur le problème :o)