Messages suspects internet explorer 7

Bonjour,

Voilà : à chaque fois que je me connecte sur IE7, je suis envahi par des messages me proposant d'analyser mon PC ("ProtectionAssurée", ...). De plus dans les réglages IE7, les cookies sont tous acceptés, réglage que je dois modifier à chaque fois.

Voici en copie le log Hijackthis:

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 16:58:29, on 25/02/2008
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v7.00 (7.00.6000.16608)
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
F:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
F:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\WINDOWS\system32\WgaTray.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\System32\taskswitch.exe
C:\WINDOWS\system32\devldr32.exe
F:\PROGRA~2\ALWILS~1\Avast4\ashDisp.exe
C:\WINDOWS\system32\RUNDLL32.EXE
C:\WINDOWS\System32\Fast.exe
C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
C:\WINDOWS\system32\nvsvc32.exe
C:\WINDOWS\System32\svchost.exe
F:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
F:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Documents and Settings\Aurélie.AUR-42C5FV46C6M\Mes documents\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.netvibes.com/en
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Search_URL = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Search Page = https://www.bing.com/?toHttps=1&redig=5FC791212101479BAFBE1A679848B1AF
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.msn.com/fr-fr/?ocid=iehp
R1 - HKLM\Software\Microsoft\Internet Explorer\SearchURL,(Default) = about:blank
R1 - HKCU\Software\Microsoft\Internet Connection Wizard,ShellNext = http://runonce.msn.com/runonce3.aspx
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
O3 - Toolbar: Easy-WebPrint - {327C2873-E90D-4c37-AA9D-10AC9BABA46C} - C:\Program Files\Canon\Easy-WebPrint\Toolband.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar4.dll
O4 - HKLM\..\Run: [FastUser] C:\WINDOWS\System32\fast.exe
O4 - HKLM\..\Run: [CoolSwitch] C:\WINDOWS\System32\taskswitch.exe
O4 - HKLM\..\Run: [BackgroundSwitcher] C:\WINDOWS\System32\bgswitch.exe
O4 - HKLM\..\Run: [QuickTime Task] "C:\program files\quicktime\qttask.exe" -atboottime
O4 - HKLM\..\Run: [avast!] F:\PROGRA~2\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [TomTomHOME.exe] "F:\Program Files\TomTom HOME 2\HOMERunner.exe" -s
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [nwiz] nwiz.exe /install
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKCU\..\Run: [swg] C:\Program Files\Google\GoogleToolbarNotifier\GoogleToolbarNotifier.exe
O4 - HKUS\S-1-5-18\..\Policies\Explorer\Run: [{B8A7334C-0681-1036-0625-040212010021}] "C:\WINDOWS\$hf_mig$\KB931836\update\update.exe" te-110-12-0000073 (User 'SYSTEM')
O4 - HKUS\.DEFAULT\..\Policies\Explorer\Run: [{B8A7334C-0681-1036-0625-040212010021}] "C:\WINDOWS\$hf_mig$\KB931836\update\update.exe" te-110-12-0000073 (User 'Default user')
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
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
O12 - Plugin for .pdf: C:\Program Files\Internet Explorer\PLUGINS\nppdf32.dll
O16 - DPF: {0246ECA8-996F-11D1-BE2F-00A0C9037DFE} (TDServer Control) - http://fr.encyclopedia.yahoo.com/rsc/tdserver.cab
O16 - DPF: {09C21411-B9A2-4DE6-8416-4E3B58577BE0} (France Telecom MDM ActiveX Control) - http://imin.cvf.fr/imin_data/ocx/MDM.cab
O16 - DPF: {2BC66F54-93A8-11D3-BEB6-00105AA9B6AE} (Symantec AntiVirus scanner) - http://security.symantec.com/sscv6/SharedContent/vc/bin/AvSniff.cab
O16 - DPF: {56336BCB-3D8A-11D6-A00B-0050DA18DE71} (RdxIE Class) - http://software-dl.real.com/076b05d600f459b8ee16/netzip/RdxIE601_fr.cab
O16 - DPF: {644E432F-49D3-41A1-8DD5-E099162EEEC5} (Symantec RuFSI Utility Class) - http://security.symantec.com/sscv6/SharedContent/common/bin/cabsa.cab
O16 - DPF: {6DB731A3-B074-4118-8B1C-32511C65D836} (FotovistaPhotoUploader.ctrFpu) - http://www.mypixmania.com/tools/activex/fpu.cab
O16 - DPF: {6E5E167B-1566-4316-B27F-0DDAB3484CF7} (Image Uploader Control) - http://copainsdavant.linternaute.com/html_include_bibliotheque/objimageuploader/ImageUploader4.cab
O16 - DPF: {CE69F98F-2AF3-4306-BAC6-A79070EDA1B4} (Zylom Loader Object) - http://game14.zylom.m6game.m6.fr/activex/zylomloader.cab
O16 - DPF: {E15111B0-95AE-4C05-B91F-F4564057990C} (MovieSystem WAY) - http://servicesv4.moviesystem.com/cabs/msway.cab
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - F:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: avast! Antivirus - ALWIL Software - F:\Program Files\Alwil Software\Avast4\ashServ.exe
O23 - Service: avast! Mail Scanner - ALWIL Software - F:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
O23 - Service: avast! Web Scanner - ALWIL Software - F:\Program Files\Alwil Software\Avast4\ashWebSv.exe
O23 - Service: Google Updater Service (gusvc) - Google - C:\Program Files\Google\Common\Google Updater\GoogleUpdaterService.exe
O23 - Service: NVIDIA Display Driver Service (NVSvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe