Virus "win32 trojan-gen other"

Bonjour a tous, voila le probleme: Avast a tout d'un coup commencer a crier en me disant qu'il a detecte le virus win32 trojan-gen other, ca m'inquiete parceque lorsqu'il l'efface, a chaque sca il reapparait sous une autre forme !
Voici le log HijackThis:

Logfile of HijackThis v1.99.1
Scan saved at 13:38:56, on 09/03/2007
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\csrss.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\System32\svchost.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\system32\ZoneLabs\vsmon.exe
C:\WINDOWS\Explorer.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\nvsvc32.exe
C:\WINDOWS\system32\wdfmgr.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\NVIDIA Corporation\NvMixer\NvMixerTray.exe
C:\Program Files\MessengerPlus! 3\MsgPlus.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe
C:\Program Files\Java\jre1.5.0_11\bin\jusched.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\system32\RunDLL32.exe
C:\Program Files\QuickTime\qttask.exe
C:\program files\powerstrip\pstrip.exe
C:\WINDOWS\system32\ctfmon.exe
C:\WINDOWS\lclock.exe
C:\WINDOWS\System32\alg.exe
C:\Program Files\Microsoft Office\Office\OSA.EXE
C:\Program Files\Microsoft Office\Office\FINDFAST.EXE
C:\Program Files\MSN Messenger\msnmsgr.exe
C:\Program Files\mozilla.org\Mozilla\mozilla.exe
C:\Program Files\QuickZip4\QuickZip.exe
C:\DOCUME~1\corto44\LOCALS~1\Temp\QZTEMP\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://www.google.fr/keyword/%s
R3 - URLSearchHook: Yahoo! Toolbar avec bloqueur de fenętres pop-up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
R3 - URLSearchHook: SweetIM For Internet Explorer - {BC4FFE41-DE9F-46fa-B455-AAD49B9F9938} - (no file)
O3 - Toolbar: Easy-WebPrint - {327C2873-E90D-4c37-AA9D-10AC9BABA46C} - C:\Program Files\Canon\Easy-WebPrint\Toolband.dll
O3 - Toolbar: SweetIM For Internet Explorer - {BC4FFE41-DE9F-46fa-B455-AAD49B9F9938} - (no file)
O3 - Toolbar: Yahoo! Toolbar avec bloqueur de fenętres pop-up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
O4 - HKLM\..\Run: [NvMixerTray] "C:\Program Files\NVIDIA Corporation\NvMixer\NvMixerTray.exe"
O4 - HKLM\..\Run: [MessengerPlus3] "C:\Program Files\MessengerPlus! 3\MsgPlus.exe"
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [Easy-PrintToolBox] "C:\Program Files\Canon\Easy-PrintToolBox\BJPSMAIN.EXE" /logon
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [BearShare] "C:\Program Files\BearShare\BearShare.exe" /pause
O4 - HKLM\..\Run: [Zone Labs Client] "C:\Program Files\Zone Labs\ZoneAlarm\zlclient.exe"
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.5.0_11\bin\jusched.exe"
O4 - HKLM\..\Run: [NvCplDaemon] "RUNDLL32.EXE" C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] "nwiz.exe" /install
O4 - HKLM\..\Run: [NvMediaCenter] "RunDLL32.exe" NvMCTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [PowerStrip] "c:\program files\powerstrip\pstrip.exe"
O4 - HKLM\..\Run: [KernelFaultCheck] %systemroot%\system32\dumprep 0 -k
O4 - HKLM\..\Run: [2chkdsk] rundll32.exe "C:\WINDOWS\system32\nvegbqtl.dll",setvm
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [LClock] lclock.exe
O4 - HKCU\..\Run: [MessengerPlus3] "C:\Program Files\MessengerPlus! 3\MsgPlus.exe" /WinStart
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\MSN Messenger\msnmsgr.exe" /background
O4 - Startup: Démarrage d'Office.lnk = C:\Program Files\Microsoft Office\Office\OSA.EXE
O4 - Startup: Microsoft Recherche accélérée.lnk = C:\Program Files\Microsoft Office\Office\FINDFAST.EXE
O4 - Global Startup: Lancement rapide d'Adobe Reader.lnk = C:\Program Files\Adobe\Acrobat 7.0\Reader\reader_sl.exe
O8 - Extra context menu item: Easy-WebPrint Ajouter ŕ 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: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_11\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_11\bin\ssv.dll
O16 - DPF: {0EB0E74A-2A76-4AB3-A7FB-9BD8C29F7F75} (CKAVWebScan Object) - http://webscanner.kaspersky.fr/kavwebscan_unicode.cab
O16 - DPF: {30528230-99f7-4bb4-88d8-fa1d4f56a2ab} (YInstStarter Class) - C:\Program Files\Yahoo!\Common\yinsthelper.dll
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - "C:\PROGRA~1\MSNMES~1\msgrapp.dll" (file missing)
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: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe
O23 - Service: TrueVector Internet Monitor (vsmon) - Zone Labs, LLC - C:\WINDOWS\system32\ZoneLabs\vsmon.exe


Je vous remercie d'avance.