Virus détecté par Antivir insupprimable

Bonjour,

Depuis quelques jours, mon ordinateur rame quelque peu. Ainsi, j'ai fait une analyse anti virus avec mon logiciel Avira Antivir et il m'a trouvé une série de 15 virus nommé TR/... mais quand je les supprime, ils reviennent, comment faire ?

J'ai fait un rapport Hijackthis si vous voulez :

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 13:34:30, on 15/04/2010
Platform: Windows Vista (WinNT 6.00.1904)
MSIE: Internet Explorer v7.00 (7.00.6000.16386)
Boot mode: Normal

Running processes:
C:\Windows\system32\Dwm.exe
C:\Windows\Explorer.EXE
C:\Windows\system32\taskeng.exe
C:\Program Files\Avira\AntiVir Desktop\avgnt.exe
C:\Program Files\Steam\Steam.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Program Files\Windows Live\Contacts\wlcomm.exe
C:\Program Files\Avira\AntiVir Desktop\avcenter.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Windows\system32\wuauclt.exe
c:\program files\avira\antivir desktop\avscan.exe
C:\Program Files\VideoLAN\VLC\vlc.exe
C:\Windows\system32\SearchFilterHost.exe
C:\Users\Jojo\Desktop\HiJackThis.exe
C:\Windows\system32\DllHost.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = http://fr.rd.yahoo.com/customize/ycomp/defaults/sp/*https://fr.yahoo.com/
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://fr.yahoo.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://fr.fr.acer.yahoo.com
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = https://fr.yahoo.com/
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,SearchAssistant =
R0 - HKLM\Software\Microsoft\Internet Explorer\Search,CustomizeSearch =
R1 - HKCU\Software\Microsoft\Internet Explorer\SearchURL,(Default) = http://fr.rd.yahoo.com/customize/ycomp/defaults/su/*https://fr.yahoo.com/
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName =
R3 - URLSearchHook: Yahoo! Toolbar avec bloqueur de fenêtres pop-up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - (no file)
O1 - Hosts: ::1 localhost
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (no file)
O2 - BHO: (no name) - {83A2F9B1-01A2-4AA5-87D1-45B6B8505E96} - (no file)
O2 - BHO: Programme d'aide de l'Assistant de connexion Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKLM\..\Run: [AdobeCS4ServiceManager] "C:\Program Files\Common Files\Adobe\CS4ServiceManager\CS4ServiceManager.exe" -launchedbylogin
O4 - HKCU\..\Run: [Steam] "c:\program files\steam\steam.exe" -silent
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKUS\S-1-5-19\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-19\..\Run: [WindowsWelcomeCenter] rundll32.exe oobefldr.dll,ShowWelcomeCenter (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [Sidebar] %ProgramFiles%\Windows Sidebar\Sidebar.exe /detectMem (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-18\..\Run: [] (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [] (User 'Default user')
O4 - Startup: enjoy.pls
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office12\EXCEL.EXE/3000
O9 - Extra button: Research - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\Office12\REFIEBAR.DLL
O13 - Gopher Prefix:
O18 - Protocol: skype4com - {FFC8B962-9B40-4DFF-9458-1830C7DD7F5D} - C:\PROGRA~1\COMMON~1\Skype\SKYPE4~1.DLL
O23 - Service: Avira AntiVir Planificateur (AntiVirSchedulerService) - Avira GmbH - C:\Program Files\Avira\AntiVir Desktop\sched.exe
O23 - Service: Avira AntiVir Guard (AntiVirService) - Avira GmbH - C:\Program Files\Avira\AntiVir Desktop\avguard.exe
O23 - Service: Ati External Event Utility - ATI Technologies Inc. - C:\Windows\system32\Ati2evxx.exe
O23 - Service: Symantec Lic NetConnect service (CLTNetCnService) - Unknown owner - c:\Program Files\Common Files\Symantec Shared\ccSvcHst.exe (file missing)
O23 - Service: eRecovery Service (eRecoveryService) - Acer Inc. - C:\Acer\Empowering Technology\eRecovery\eRecoveryService.exe
O23 - Service: Firebird Guardian - DefaultInstance (FirebirdGuardianDefaultInstance) - Firebird Project - C:\Program Files\Firebird\Firebird_2_1\bin\fbguard.exe
O23 - Service: Firebird Server - DefaultInstance (FirebirdServerDefaultInstance) - Firebird Project - C:\Program Files\Firebird\Firebird_2_1\bin\fbserver.exe
O23 - Service: FLEXnet Licensing Service - Acresso Software Inc. - C:\Program Files\Common Files\Macrovision Shared\FLEXnet Publisher\FNPLicensingService.exe
O23 - Service: LightScribeService Direct Disc Labeling Service (LightScribeService) - Hewlett-Packard Company - C:\Program Files\Common Files\LightScribe\LSSrvc.exe
O23 - Service: Steam Client Service - Valve Corporation - C:\Program Files\Common Files\Steam\SteamService.exe