[virus] impossible à supprimer

bonjour,
mon pc est infecté par plusieurs virus (via msn) dont je ne parviens pas à me débarasser. il s'agit de : Win32:winfixer-f et Win32:agent-ISI détectés par Avast. pouvez-vous m'indiquer la marche à suivre ? merci pour votre aide.

je poste ici le rapport de Hijackthis:

Logfile of HijackThis v1.99.1
Scan saved at 15:31:30, on 12/07/2007
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\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:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\ehome\ehtray.exe
C:\Program Files\hpq\HP Wireless Assistant\HP Wireless Assistant.exe
C:\Program Files\Java\jre1.6.0_01\bin\jusched.exe
C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
C:\Program Files\HP\QuickPlay\QPService.exe
C:\Program Files\Hp\HP Software Update\HPWuSchd2.exe
C:\Program Files\Hewlett-Packard\HP Quick Launch Buttons\QlbCtrl.exe
C:\Program Files\Winamp\winampa.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\MSN Messenger\MsnMsgr.Exe
C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
C:\Program Files\Windows Media Player\WMPNSCFG.exe
C:\Program Files\HP\Digital Imaging\bin\hpqimzone.exe
C:\WINDOWS\eHome\ehRecvr.exe
C:\WINDOWS\eHome\ehSched.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Fichiers communs\LightScribe\LSSrvc.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\WINDOWS\system32\svchost.exe
C:\Program Files\Hewlett-Packard\Shared\hpqwmiex.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\WINDOWS\system32\dllhost.exe
C:\WINDOWS\eHome\ehmsas.exe
C:\Program Files\MSN Messenger\usnsvc.exe
C:\Program Files\eMule\emule.exe
C:\Program Files\Internet Explorer\IEXPLORE.EXE
C:\Documents and Settings\Emilie\Bureau\HijackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://fr.yahoo.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://www.msn.com/fr-fr?cobrand=hp-notebook.msn.com&ocid=HPDHP&pc=HPNTDF
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = https://www.msn.com/fr-fr?cobrand=hp-notebook.msn.com&ocid=HPDHP&pc=HPNTDF
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_01\bin\ssv.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar2.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.0.301.7164\swg.dll
O2 - BHO: EpsonToolBandKicker Class - {E99421FB-68DD-40F0-B4AC-B7027CAE2F1A} - C:\Program Files\EPSON\EPSON Web-To-Page\EPSON Web-To-Page.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar2.dll
O3 - Toolbar: EPSON Web-To-Page - {EE5D279F-081B-4404-994D-C6B60AAEBA6D} - C:\Program Files\EPSON\EPSON Web-To-Page\EPSON Web-To-Page.dll
O4 - HKLM\..\Run: [ehTray] C:\WINDOWS\ehome\ehtray.exe
O4 - HKLM\..\Run: [hpWirelessAssistant] C:\Program Files\hpq\HP Wireless Assistant\HP Wireless Assistant.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre1.6.0_01\bin\jusched.exe"
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [MsmqIntCert] regsvr32 /s mqrt.dll
O4 - HKLM\..\Run: [High Definition Audio Property Page Shortcut] CHDAudPropShortcut.exe
O4 - HKLM\..\Run: [SynTPEnh] C:\Program Files\Synaptics\SynTP\SynTPEnh.exe
O4 - HKLM\..\Run: [QPService] "C:\Program Files\HP\QuickPlay\QPService.exe"
O4 - HKLM\..\Run: [HP Software Update] C:\Program Files\Hp\HP Software Update\HPWuSchd2.exe
O4 - HKLM\..\Run: [QlbCtrl] %ProgramFiles%\Hewlett-Packard\HP Quick Launch Buttons\QlbCtrl.exe /Start
O4 - HKLM\..\Run: [Cpqset] C:\Program Files\HPQ\Default Settings\cpqset.exe
O4 - HKLM\..\Run: [RecGuard] C:\Windows\SMINST\RecGuard.exe
O4 - HKLM\..\Run: [EPSON Stylus DX4000 Series] C:\WINDOWS\System32\spool\DRIVERS\W32X86\3\E_FATIBEE.EXE /FU "C:\WINDOWS\TEMP\E_S96.tmp" /EF "HKLM"
O4 - HKLM\..\Run: [WinampAgent] C:\Program Files\Winamp\winampa.exe
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [MsnMsgr] "C:\Program Files\MSN Messenger\MsnMsgr.Exe" /background
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - HKCU\..\Run: [WMPNSCFG] C:\Program Files\Windows Media Player\WMPNSCFG.exe
O4 - Global Startup: Démarrage rapide de HP Photosmart Premier.lnk = C:\Program Files\HP\Digital Imaging\bin\hpqthb08.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: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~3\Office12\EXCEL.EXE/3000
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: (no name) - {85d1f590-48f4-11d9-9669-0800200c9a66} - %windir%\bdoscandel.exe (file missing)
O9 - Extra 'Tools' menuitem: Uninstall BitDefender Online Scanner v8 - {85d1f590-48f4-11d9-9669-0800200c9a66} - %windir%\bdoscandel.exe (file missing)
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~3\Office12\REFIEBAR.DLL
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
O14 - IERESET.INF: START_PAGE_URL=https://www.msn.com/fr-fr?cobrand=hp-notebook.msn.com&ocid=HPDHP&pc=HPNTDF
O16 - DPF: {5D86DDB5-BDF9-441B-9E9E-D4730F4EE499} (BDSCANONLINE Control) - http://download.bitdefender.com/resources/scan8/oscan8.cab
O18 - Protocol: livecall - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\MSNMES~1\MSGRAP~1.DLL
O18 - Protocol: ms-help - {314111C7-A502-11D2-BBCA-00C04F8EC294} - C:\Program Files\Fichiers communs\Microsoft Shared\Help\hxds.dll
O18 - Protocol: msnim - {828030A1-22C1-4009-854F-8E305202313F} - C:\PROGRA~1\MSNMES~1\MSGRAP~1.DLL
O18 - Filter hijack: text/xml - {807563E5-5146-11D5-A672-00B0D022E945} - C:\PROGRA~1\FICHIE~1\MICROS~1\OFFICE12\MSOXMLMF.DLL
O20 - Winlogon Notify: WgaLogon - C:\WINDOWS\SYSTEM32\WgaLogon.dll
O21 - SSODL: WPDShServiceObj - {AAA288BA-9A4C-45B0-95D7-94D524869DB5} - C:\WINDOWS\system32\WPDShServiceObj.dll
O23 - Service: AddFiltr - Hewlett-Packard Development Company, L.P. - C:\Program Files\Hewlett-Packard\HP Quick Launch Buttons\AddFiltr.exe
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - 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: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: hpqwmiex - Hewlett-Packard Development Company, L.P. - C:\Program Files\Hewlett-Packard\Shared\hpqwmiex.exe
O23 - Service: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - c:\Program Files\Fichiers communs\InstallShield\Driver\1050\Intel 32\IDriverT.exe
O23 - Service: LightScribeService Direct Disc Labeling Service (LightScribeService) - Hewlett-Packard Company - C:\Program Files\Fichiers communs\LightScribe\LSSrvc.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe