Bon,
En attendant de l'aide j'ai fait un scan hijacthis dont voici le rapport.
Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 18:46:12, on 12/02/2011
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.17055)
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\Ati2evxx.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Avira\AntiVir Desktop\sched.exe
C:\WINDOWS\system32\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\ATI-CPanel\atiptaxx.exe
C:\Program Files\QuickTime\qttask.exe
C:\Program Files\Adobe\Adobe Version Cue\ControlPanel\VersionCueTray.exe
C:\PROGRA~1\Wanadoo\TaskBarIcon.exe
C:\Program Files\Java\jre6\bin\jusched.exe
C:\Program Files\Avira\AntiVir Desktop\avgnt.exe
C:\Program Files\Fichiers communs\InstallShield\UpdateService\issch.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Messenger\msmsgs.exe
C:\Program Files\SAGEM\SAGEM F@st 800-840\dslmon.exe
C:\Program Files\Micro Application\LauncherMA.exe
C:\Program Files\Avira\AntiVir Desktop\avguard.exe
C:\WINDOWS\System32\FTRTSVC.exe
C:\Program Files\Java\jre6\bin\jqs.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Program Files\Java\jre6\bin\jucheck.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Documents and Settings\BUT EXPO\Bureau\HiJackThis.exe
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page =
http://www.orange.fr/
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
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 =
http://go.microsoft.com/fwlink/?LinkId=69157
R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Window Title = Orange
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
R3 - URLSearchHook: Search Class - {08C06D61-F1F3-4799-86F8-BE1A89362C85} - C:\PROGRA~1\Wanadoo\SEARCH~1.DLL
R3 - URLSearchHook: Audacity-tools Toolbar - {d0b1518e-3e45-4d16-a23b-4d90ef938e44} - C:\Program Files\Audacity-tools\tbAud2.dll
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: Conduit Engine - {30F9B915-B755-4826-820B-08FBA6BD249D} - C:\Program Files\ConduitEngine\ConduitEngine.dll
O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (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
O2 - BHO: Audacity-tools Toolbar - {d0b1518e-3e45-4d16-a23b-4d90ef938e44} - C:\Program Files\Audacity-tools\tbAud2.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre6\bin\jp2ssv.dll
O2 - BHO: JQSIEStartDetectorImpl - {E7E6F031-17CE-4C07-BC86-EABFE594F69C} - C:\Program Files\Java\jre6\lib\deploy\jqs\ie\jqs_plugin.dll
O3 - Toolbar: Audacity-tools Toolbar - {d0b1518e-3e45-4d16-a23b-4d90ef938e44} - C:\Program Files\Audacity-tools\tbAud2.dll
O4 - HKLM\..\Run: [ATIPTA] C:\ATI-CPanel\atiptaxx.exe
O4 - HKLM\..\Run: [NeroCheck] C:\WINDOWS\system32\NeroCheck.exe
O4 - HKLM\..\Run: [WOOWATCH] C:\PROGRA~1\Wanadoo\Watch.exe
O4 - HKLM\..\Run: [WOOTASKBARICON] C:\PROGRA~1\Wanadoo\GestMaj.exe TaskBarIcon.exe
O4 - HKLM\..\Run: [REGSHAVE] C:\Program Files\REGSHAVE\REGSHAVE.EXE /AUTORUN
O4 - HKLM\..\Run: [QuickTime Task] "C:\Program Files\QuickTime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [AdobeVersionCue] C:\Program Files\Adobe\Adobe Version Cue\ControlPanel\VersionCueTray.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre6\bin\jusched.exe"
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Program Files\Adobe\Reader 8.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [ISUSPM Startup] C:\PROGRA~1\FICHIE~1\INSTAL~1\UPDATE~1\isuspm.exe -startup
O4 - HKLM\..\Run: [ISUSScheduler] "C:\Program Files\Fichiers communs\InstallShield\UpdateService\issch.exe" -start
O4 - HKCU\..\Run: [CTFMON.EXE] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [WOOKIT] C:\PROGRA~1\Wanadoo\GestMaj.exe EspaceWanadoo.exe
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - HKUS\S-1-5-19\..\Run: [CTFMON.EXE] C:\WINDOWS\System32\CTFMON.EXE (User 'SERVICE LOCAL')
O4 - HKUS\S-1-5-20\..\Run: [CTFMON.EXE] C:\WINDOWS\System32\CTFMON.EXE (User 'SERVICE RÉSEAU')
O4 - HKUS\S-1-5-18\..\Run: [CTFMON.EXE] C:\WINDOWS\System32\CTFMON.EXE (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Run: [CTFMON.EXE] C:\WINDOWS\System32\CTFMON.EXE (User 'Default user')
O4 - Startup: Lanceur.lnk = C:\Program Files\Micro Application\LauncherMA.exe
O4 - Global Startup: Adobe Gamma Loader.lnk = C:\Program Files\Fichiers communs\Adobe\Calibration\Adobe Gamma Loader.exe
O4 - Global Startup: DSLMON.lnk = C:\Program Files\SAGEM\SAGEM F@st 800-840\dslmon.exe
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\OFFICE11\EXCEL.EXE/3000
O9 - Extra button: Recherche - {92780B25-18CC-41C8-B9BE-3C9C571A8263} - C:\PROGRA~1\MICROS~2\OFFICE11\REFIEBAR.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
O9 - Extra button: Orange - {1462651F-F4BA-4C76-A001-C4284D0FE16E} -
http://www.orange.fr (file missing) (HKCU)
O16 - DPF: {28B66320-9687-4B13-8757-36F901887AB5} (CanvasX Class) -
http://photoservice.fujicolor.eu/ips-opdata/layout/aspadmin/objects/canvasx.cab
O16 - DPF: {B79A53C0-1DAC-4636-BACE-FD086A7A79BF} (AdSignerLCContrl Class) -
https://static.impots.gouv.fr/tdir/static/adpform/AdSignerADP-2.0.cab
O16 - DPF: {CAFEEFAC-0014-0000-0003-ABCDEFFEDCBA} (Environnement d'exécution Java 1.4.0_03) -
O23 - Service: Adobe LM Service - Unknown owner - C:\Program Files\Fichiers communs\Adobe Systems Shared\Service\Adobelmsvc.exe
O23 - Service: AdobeVersionCue - Adobe Sytems - C:\Program Files\Adobe\Adobe Version Cue\service\VersionCue.exe
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 HotKey Poller - ATI Technologies Inc. - C:\WINDOWS\System32\Ati2evxx.exe
O23 - Service: France Telecom Routing Table Service (FTRTSVC) - France Telecom - C:\WINDOWS\System32\FTRTSVC.exe
O23 - Service: Google Update Service (gupdate) (gupdate) - Google Inc. - C:\Program Files\Google\Update\GoogleUpdate.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Sun Microsystems, Inc. - C:\Program Files\Java\jre6\bin\jqs.exe