bonsoir,
je suis en galère depuis quelques jours... 
après avoir fait des mise à jour sp2 et avoir installé avast antivirus, je n'ai plus accès à mon bureau ni à aucun autre dossier ou logiciel. j'ai accès à internet (firefox) que par le biais le gestionnaire des tâches. après avoir démarré mon pc j'ai un message d'erreur me disant que explorer n'a pas pu s'ouvrir.
je ne peux pas faire de scan antivirus en ligne (firefox) ni par le mien (avast)... 
j'ai pu faire un scan hijtachis, voici le résultat
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 20:54:34, on 14/08/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16705)
Boot mode: Normal
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:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\System32\drivers\CDAC11BA.EXE
C:\Program Files\Fichiers communs\Microsoft Shared\VS7Debug\mdm.exe
C:\WINDOWS\System32\HPZipm12.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\PROGRA~1\MOZILL~1\FIREFOX.EXE
C:\Program Files\Microsoft Office\Office10\WINWORD.EXE
C:\WINDOWS\system32\ctfmon.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Documents and Settings\ADMIN\Bureau\HiJackThis.exe
C:\WINDOWS\system32\TASKMAN.EXE
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://fr.msn.com/
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = http://go.microsoft.com/fwlink/?LinkId=54896
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = http://go.microsoft.com/fwlink/?LinkId=69157
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
R3 - URLSearchHook: Yahoo! Toolbar avec bloqueur de fenêtres pop-up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: Yahoo! Toolbar Helper - {02478D38-C3F9-4EFB-9B51-7695ECA05670} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
O2 - BHO: AcroIEHlprObj Class - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: RealPlayer Download and Record Plugin for Internet Explorer - {3049C3E9-B461-4BC5-8870-4C09146192CA} - C:\Program Files\Real\RealPlayer\rpbrowserrecordplugin.dll
O2 - BHO: (no name) - {59879FA4-4790-461c-A1CC-4EC4DE4CA483} - (no file)
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.5.0_06\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Programme d'aide de l'Assistant de connexion Windows Live - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Fichiers communs\Microsoft Shared\Windows Live\WindowsLiveLogin.dll
O3 - Toolbar: Yahoo! Toolbar avec bloqueur de fenêtres pop-up - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\Program Files\Yahoo!\Companion\Installs\cpn\yt.dll
O4 - HKLM\..\Run: [HP Software Update] "C:\Program Files\HP\HP Software Update\HPWuSchd2.exe"
O4 - HKLM\..\Run: [HP Component Manager] "C:\Program Files\HP\hpcoretech\hpcmpmgr.exe"
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [TkBellExe] "C:\Program Files\Fichiers communs\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_2] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmnetmgr.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_3] C:\WINDOWS\System32\regsvr32 /s /u "C:\WINDOWS\System32\wmv8dmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_4] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmvdmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_5] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmvdmoe2.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_6] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmadmoe.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_7] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmspdmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_8] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmspdmoe.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_9] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmsdmoe.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_10] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmsdmoe2.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_20] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmadmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_21] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\mpg4dmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_22] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\mp43dmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_23] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\mp4sdmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_24] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmsdmod.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_30] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\laprxy.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_31] "C:\WINDOWS\System32\logagent.exe" /RegServer
O4 - HKLM\..\RunOnce: [OE_WMPWMFSDK_Install_32] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\wmvcore.dll"
O4 - HKLM\..\RunOnce: [OE_WMPDRM_Install_1] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\drmstor.dll"
O4 - HKLM\..\RunOnce: [OE_WMPDRM_Install_2] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\drmclien.dll"
O4 - HKLM\..\RunOnce: [OE_WMPDRM_Install_4] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\drmv2clt.dll"
O4 - HKLM\..\RunOnce: [OE_WMPDRM_Install_5] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\blackbox.dll"
O4 - HKLM\..\RunOnce: [OE_WMPDRM_Install_6] C:\WINDOWS\System32\regsvr32 /s "C:\WINDOWS\System32\msnetobj.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_0] C:\WINDOWS\INF\unregmp2.exe /MigrateLibrary
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_1] "C:\Program Files\Windows Media Player\migrate.exe" /s
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_2] C:\WINDOWS\System32\regsvr32 /s C:\WINDOWS\System32\wmp.dll
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_8] C:\WINDOWS\System32\regsvr32 /s C:\WINDOWS\System32\wmpshell.dll
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_9] C:\WINDOWS\System32\regsvr32 /s C:\WINDOWS\System32\wmpasf.dll
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_10] C:\WINDOWS\System32\regsvr32 /s C:\WINDOWS\System32\wmpdxm.dll
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_11] C:\WINDOWS\System32\regsvr32 /s "C:\Program Files\Windows Media Player\mpvis.dll"
O4 - HKLM\..\RunOnce: [OE_WMPWMDM_Install_7] C:\WINDOWS\System32\regsvr32 /s C:\WINDOWS\System32\mspmsnsv.dll
O4 - HKLM\..\RunOnce: [OE_WMPWMP7_Install_20] C:\WINDOWS\INF\unregmp2.exe /Shortcuts /RegExts
O4 - HKLM\..\RunOnce: [NoIE4StubProcessing] C:\WINDOWS\system32\reg.exe DELETE "HKLM\SOFTWARE\Microsoft\Active Setup\Installed Components" /v "NoIE4StubProcessing" /f
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [LDM] \Program\
O4 - HKCU\..\Run: [MsnMsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background
O4 - HKCU\..\Run: [updateMgr] "C:\Program Files\Adobe\Acrobat 7.0\Reader\AdobeUpdateManager.exe" AcRdB7_0_7 -reboot 1
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - Global Startup: Logitech Desktop Messenger.lnk = C:\Program Files\Logitech\Desktop Messenger\8876480\Program\LDMConf.exe
O4 - Global Startup: Logitech SetPoint.lnk = C:\Program Files\Logitech\SetPoint\SetPoint.exe
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office10\OSA.EXE
O8 - Extra context menu item: &Search - http://ko.bar.need2find.com/KO/menusearch.html?p=KO
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office10\EXCEL.EXE/3000
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_06\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_06\bin\ssv.dll
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\WINDOWS\system32\shdocvw.dll
O9 - Extra button: (no name) - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
O9 - Extra 'Tools' menuitem: @xpsp3res.dll,-20001 - {e2e2dd38-d088-4134-82b7-f2ba38496583} - C:\WINDOWS\Network Diagnostic\xpnetdiag.exe
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
O10 - Unknown file in Winsock LSP: c:\windows\system32\nwprovau.dll
O12 - Plugin for .tif: C:\Program Files\Internet Explorer\PLUGINS\npqtplugin7.dll
O16 - DPF: {0CCA191D-13A6-4E29-B746-314DEE697D83} (Facebook Photo Uploader 5) - http://upload.facebook.com/control [...] oader5.cab
O16 - DPF: {30528230-99f7-4bb4-88d8-fa1d4f56a2ab} (YInstStarter Class) - C:\Program Files\Yahoo!\Common\yinsthelper.dll
O16 - DPF: {4F1E5B1A-2A80-42CA-8532-2D05CB959537} (MSN Photo Upload Tool) - http://gfx1.hotmail.com/mail/w2/resources/MSNPUpld.cab
O16 - DPF: {56336BCB-3D8A-11D6-A00B-0050DA18DE71} - http://software-dl.real.com/09dacc [...] 601_fr.cab
O16 - DPF: {5C6698D9-7BE4-4122-8EC5-291D84DBD4A0} (Facebook Photo Uploader 4 Control) - http://upload.facebook.com/control [...] oader3.cab
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://v5.windowsupdate.microsoft. [...] 8256568781
O16 - DPF: {74D05D43-3236-11D4-BDCD-00C04F9A3B61} (HouseCall Control) - http://a840.g.akamai.net/7/840/537 [...] scan53.cab
O16 - DPF: {88764F69-3831-4EC1-B40B-FF21D8381345} (AdVerifierADPCtrl Class) - https://static.impots.gouv.fr/tdir/ [...] DP-1.0.cab
O16 - DPF: {8E0D4DE5-3180-4024-A327-4DFAD1796A8D} (MessengerStatsClient Class) - http://messenger.zone.msn.com/bina [...] b31267.cab
O16 - DPF: {B79A53C0-1DAC-4636-BACE-FD086A7A79BF} (AdSignerLCContrl Class) - https://static.impots.gouv.fr/tdir/ [...] DP-1.1.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{68736571-137A-476D-982D-E43F6119C150}: NameServer = 208.67.220.220,208.67.222.222
O17 - HKLM\System\CCS\Services\Tcpip\..\{B4B82F1B-AD99-45FE-A746-27F7D14D5BDD}: NameServer = 208.67.220.220,208.67.222.222
O17 - HKLM\System\CS1\Services\Tcpip\Parameters: NameServer = 208.67.220.220,208.67.222.222
O17 - HKLM\System\CS1\Services\Tcpip\..\{68736571-137A-476D-982D-E43F6119C150}: NameServer = 208.67.220.220,208.67.222.222
O17 - HKLM\System\CCS\Services\Tcpip\Parameters: NameServer = 208.67.220.220,208.67.222.222
O18 - Protocol: offline-8876480 - {C976735E-BB82-4BF8-8587-4916054FA28F} - C:\Program Files\Logitech\Desktop Messenger\8876480\Program\BWPlugProtocol-8876480.dll
O18 - Filter hijack: text/html - {2AB289AE-4B90-4281-B2AE-1F4BB034B647} - (no file)
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 - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
O23 - Service: avast! Web Scanner - ALWIL Software - C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
O23 - Service: C-DillaCdaC11BA - Macrovision - C:\WINDOWS\System32\drivers\CDAC11BA.EXE
O23 - Service: Pml Driver HPZ12 - HP - C:\WINDOWS\System32\HPZipm12.exe
O23 - Service: TuneUp Drive Defrag Service (TuneUp.Defrag) - TuneUp Software GmbH - C:\WINDOWS\System32\TuneUpDefragService.exe
--
End of file - 11853 bytes
merci de votre aide, HELPP 
!