Après quelques conseil lu sur le forum, voici le rapportde HijackThis
Si cela peut aider !

Logfile of HijackThis v1.99.1
Scan saved at 18:05:42, on 03/08/2008
Platform: Windows 2000 SP4 (WinNT 5.00.2195)
MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)

Running processes:
C:\WINNT\System32\smss.exe
C:\WINNT\system32\winlogon.exe
C:\WINNT\system32\services.exe
C:\WINNT\system32\lsass.exe
C:\WINNT\system32\svchost.exe
C:\WINNT\system32\spoolsv.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINNT\System32\svchost.exe
C:\WINNT\system32\HPZipm12.exe
C:\WINNT\system32\regsvc.exe
C:\WINNT\system32\MSTask.exe
C:\Program Files\SPAMfighter\sfus.exe
C:\WINNT\system32\stisvc.exe
C:\WINNT\System32\WBEM\WinMgmt.exe
C:\WINNT\system32\mspmspsv.exe
C:\WINNT\system32\svchost.exe
C:\WINNT\Explorer.EXE
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Program Files\SPAMfighter\SFAgent.exe
C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe­
C:\PROGRA~1\MICROS~2\Office\OUTLOOK.EXE
C:\WINNT\msagent\AgentSvr.exe
C:\Program Files\Internet Explorer\IEXPLORE.EXE
C:\PROGRA~1\Nokia\NOKIAP~1\VFSWRA~1.EXE
C:\PROGRA~1\FICHIE~1\PCSuite\DATALA~1\DATALA~1.EXE
C:\PROGRA~1\FICHIE~1\PCSuite\Services\SERVIC~1.EXE
C:\Program Files\Internet Explorer\IEXPLORE.EXE
C:\Program Files\WinRAR\WinRAR.exe
C:\DOCUME~1\ADMINI~1\LOCALS~1\Temp\Rar$EX01.219\HijackThis.e­xe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://news.google.fr/nwshp?hl=fr&tab=wn
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O2 - BHO: Aide pour le lien d'Adobe PDF Reader - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Fichiers communs\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.6.0_05\bin\ssv.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar1.dll
O2 - BHO: Google Toolbar Notifier BHO - {AF69DE43-7D58-4638-B6FA-CE66B5AD205D} - C:\Program Files\Google\GoogleToolbarNotifier\2.0.301.7164\swg.dll
O3 - Toolbar: &Radio - {8E718888-423F-11D2-876E-00A0C9082467} - C:\WINNT\System32\msdxm.ocx
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar1.dll
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [SPAMfighter Agent] "C:\Program Files\SPAMfighter\SFAgent.exe" update delay 60
O4 - HKLM\..\Run: [Synchronization Manager] mobsync.exe /logon
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office\OSA9.EXE
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_05\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.6.0_05\bin\ssv.dll
O9 - Extra button: Related - {c95fe080-8f5d-11d2-a20b-00aa003c157a} - C:\WINNT\web\related.htm
O9 - Extra 'Tools' menuitem: Show &Related Links - {c95fe080-8f5d-11d2-a20b-00aa003c157a} - C:\WINNT\web\related.htm
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://www.update.microsoft.com/...
O16 - DPF: {6E32070A-766D-4EE6-879C-DC1FA91D2FC3} (MUWebControl Class) - http://www.update.microsoft.com/...
O16 - DPF: {867E13F2-7F31-44FB-AC97-CD38E0DC46EF} - http://fichiers.touslesdrivers.com/...
O16 - DPF: {A93B47FD-9BF6-4DA8-97FC-9270B9D64A6C} (VaPgCtrl Class) - http://www.normandie-webcam.com/plugins/h263ctrl20013/h263ctrl.cab
O16 - DPF: {CAFEEFAC-0015-0000-0000-ABCDEFFEDCBA} (Java Runtime Environment 1.5.0) - https://java.sun.com/update/1.5.0/jinstall-1_5_0-windows-i586.cab
O18 - Protocol: compta - {365B8213-2402-48CF-9907-A4E4A757DE38} - C:\isacowp\coNetIE.ocx
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: Service d'administration du Gestionnaire de disque logique (dmadmin) - VERITAS Software Corp. - C:\WINNT\System32\dmadmin.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: Pml Driver HPZ12 - HP - C:\WINNT\system32\HPZipm12.exe
O23 - Service: SPAMfighter Update Service - SPAMfighter ApS - C:\Program Files\SPAMfighter\sfus.exe

Ma messagerie suivant le courriel me donnent des textes ou les voyelles sont remplacées par des carrés
Que faut il faire au secours
jojo