Je n ai plus d antivirus ni d antispyware

Bonjour à tous!
Je ne suis pas tres calé en informatique donc je m excuse par avance si mes question sont betes.

J ai un pc avec window xp sp2, intel celeron 2.53GHz.

Depuis quelques jours je n arrive pas à uriliser spybot ni kaspersky ni AVG. Ca m affichait "raccourci manquant" j'ai desinstallé les 3 avec CCleaner puis reinstallé kaspersky mais là mon pc reboot pendant l installation.
J ai essayé kaspersky analyse online mais là aussi ça fait redemarrer le pc au bout de quelques minutes
J ai voulu reinstallé AVG mais pendant l installation j ai un message d erreur "Erreur lors de l ouverture du fichier en ecriture:
C:\program files\grisoft\AVG Anti-Spyware 7.5\guard.exe" et je suis obligé d abandonner.

J ai essayé le hijackthis et voila ce qui en sort:

Logfile of Trend Micro HijackThis v2.0.0 (BETA)
Scan saved at 18:54:40, on 18/08/2007
Platform: Windows XP SP2 (WinNT 5.01.2600)
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:\WINDOWS\system32\LEXBCES.EXE
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\system32\LEXPPS.EXE
C:\WINDOWS\EXPLORER.EXE
C:\WINDOWS\Explorer.EXE
C:\Program Files\Executive Software\DiskeeperLite\DKService.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\SOUNDMAN.EXE
C:\WINDOWS\system32\VTTimer.exe
C:\WINDOWS\system32\VTtrayp.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Internet Explorer\iexplore.exe
C:\Documents and Settings\lucy\Bureau\HiJackThis_v2.exe
C:\Program Files\MSN Messenger\msnmsgr.exe
C:\Program Files\MSN Messenger\usnsvc.exe
C:\Documents and Settings\lucy\Bureau\avgas-setup-7.5.1.43.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.google.fr/?gws_rd=ssl
F2 - REG:system.ini: UserInit=userinit.exe,EXPLORER.EXE
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Adobe\Acrobat 7.0\ActiveX\AcroIEHelper.dll
O2 - BHO: (no name) - {724d43a9-0d85-11d4-9908-00400523e39a} - C:\Program Files\Siber Systems\AI RoboForm\roboform.dll
O2 - BHO: SSVHelper Class - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre1.5.0_10\bin\ssv.dll
O2 - BHO: Google Toolbar Helper - {AA58ED58-01DD-4d91-8333-CF10577473F7} - c:\program files\google\googletoolbar3.dll
O3 - Toolbar: &Google - {2318C2B1-4965-11d4-9B18-009027A5CD4F} - c:\program files\google\googletoolbar3.dll
O3 - Toolbar: &RoboForm - {724d43a0-0d85-11d4-9908-00400523e39a} - C:\Program Files\Siber Systems\AI RoboForm\roboform.dll
O4 - HKLM\..\Run: [SoundMan] SOUNDMAN.EXE
O4 - HKLM\..\Run: [VTTimer] VTTimer.exe
O4 - HKLM\..\Run: [VTTrayp] VTtrayp.exe
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.exe
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\MSN Messenger\msnmsgr.exe" /background
O8 - Extra context menu item: Add to AMV Convert Tool... - C:\Program Files\MP3 Player Utilities 4.00\AMVConverter\grab.html
O8 - Extra context menu item: Barre RoboForm - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComShowToolbar.html
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~2\OFFICE11\EXCEL.EXE/3000
O8 - Extra context menu item: E&xporter vers Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office12\EXCEL.EXE/3000
O8 - Extra context menu item: Enregistrer le formulaire - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComSavePass.html
O8 - Extra context menu item: MediaManager tool grab multimedia file - C:\Program Files\MP3 Player Utilities 4.00\MediaManager\grab.html
O8 - Extra context menu item: Personnaliser le menu - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComCustomizeIEMenu.html
O8 - Extra context menu item: Remplir le formulaire - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComFillForms.html
O9 - Extra button: (no name) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_10\bin\ssv.dll
O9 - Extra 'Tools' menuitem: Console Java (Sun) - {08B0E5C0-4FCB-11CF-AAA5-00401C608501} - C:\Program Files\Java\jre1.5.0_10\bin\ssv.dll
O9 - Extra button: Remplir - {320AF880-6646-11D3-ABEE-C5DBF3571F46} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComFillForms.html
O9 - Extra 'Tools' menuitem: Remplir le formulaire - {320AF880-6646-11D3-ABEE-C5DBF3571F46} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComFillForms.html
O9 - Extra button: Enregistrer - {320AF880-6646-11D3-ABEE-C5DBF3571F49} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComSavePass.html
O9 - Extra 'Tools' menuitem: Enregistrer le formulaire - {320AF880-6646-11D3-ABEE-C5DBF3571F49} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComSavePass.html
O9 - Extra button: Barre RoboForm - {724d43aa-0d85-11d4-9908-00400523e39a} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComShowToolbar.html
O9 - Extra 'Tools' menuitem: Barre RoboForm - {724d43aa-0d85-11d4-9908-00400523e39a} - file://C:\Program Files\Siber Systems\AI RoboForm\RoboFormComShowToolbar.html
O9 - Extra button: (no name) - {85d1f590-48f4-11d9-9669-0800200c9a66} - %windir%\bdoscandel.exe (file missing)
O9 - Extra 'Tools' menuitem: Uninstall BitDefender Online Scanner v8 - {85d1f590-48f4-11d9-9669-0800200c9a66} - %windir%\bdoscandel.exe (file missing)
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
O16 - DPF: {0EB0E74A-2A76-4AB3-A7FB-9BD8C29F7F75} (CKAVWebScan Object) - https://www.kaspersky.fr/?domain=webscanner.kaspersky.fr
O16 - DPF: {4F1E5B1A-2A80-42CA-8532-2D05CB959537} (MSN Photo Upload Tool) - http://gfx1.mail.live.com/mail/w1/resources/MSNPUpld.cab
O16 - DPF: {5D86DDB5-BDF9-441B-9E9E-D4730F4EE499} (BDSCANONLINE Control) - http://download.bitdefender.com/resources/scan8/oscan8.cab
O16 - DPF: {9A9307A0-7DA4-4DAF-B042-5009F29E09E1} (ActiveScan Installer Class) - http://acs.pandasoftware.com/activescan/as5free/asinst.cab
O16 - DPF: {CF40ACC5-E1BB-4AFF-AC72-04C2F616BCA7} (get_atlcom Class) - http://www.adobe.com/products/acrobat/nos/gp.cab
O22 - SharedTaskScheduler: Pré-chargeur Browseui - {438755C2-A8BA-11D1-B96B-00A0C90312E1} - C:\WINDOWS\system32\browseui.dll
O22 - SharedTaskScheduler: Démon de cache des catégories de composant - {8C7461EF-2B13-11d2-BE35-3078302C2030} - C:\WINDOWS\system32\browseui.dll
O23 - Service: a-squared Anti-Malware Service (a2AntiMalware) - Unknown owner - C:\Program Files\a-squared Anti-Malware\a2service.exe (file missing)
O23 - Service: a-squared Free Service (a2free) - Unknown owner - C:\Program Files\a-squared Free\a2service.exe (file missing)
O23 - Service: Adobe LM Service - Adobe Systems - C:\Program Files\Fichiers communs\Adobe Systems Shared\Service\Adobelmsvc.exe
O23 - Service: AVG Anti-Spyware Guard - Unknown owner - C:\Program Files\Grisoft\AVG Anti-Spyware 7.5\guard.exe (file missing)
O23 - Service: Diskeeper - Executive Software International, Inc. - C:\Program Files\Executive Software\DiskeeperLite\DKService.exe
O23 - Service: Service d'administration du Gestionnaire de disque logique (dmadmin) - Unknown owner - C:\WINDOWS\System32\dmadmin.exe
O23 - Service: Journal des événements (Eventlog) - Unknown owner - C:\WINDOWS\system32\services.exe
O23 - Service: Service COM de gravage de CD IMAPI (ImapiService) - Unknown owner - C:\WINDOWS\system32\imapi.exe
O23 - Service: Service de l'iPod (iPod Service) - Unknown owner - C:\Program Files\iPod\bin\iPodService.exe (file missing)
O23 - Service: LexBce Server (LexBceS) - Lexmark International, Inc. - C:\WINDOWS\system32\LEXBCES.EXE
O23 - Service: Partage de Bureau à distance NetMeeting (mnmsrvc) - Unknown owner - C:\WINDOWS\system32\mnmsrvc.exe
O23 - Service: NBService - Nero AG - C:\Program Files\Nero\Nero 7\Nero BackItUp\NBService.exe
O23 - Service: Plug-and-Play (PlugPlay) - Unknown owner - C:\WINDOWS\system32\services.exe
O23 - Service: Gestionnaire de session d'aide sur le Bureau à distance (RDSessMgr) - Unknown owner - C:\WINDOWS\system32\sessmgr.exe
O23 - Service: Carte à puce (SCardSvr) - Unknown owner - C:\WINDOWS\System32\SCardSvr.exe
O23 - Service: Journaux et alertes de performance (SysmonLog) - Unknown owner - C:\WINDOWS\system32\smlogsvc.exe
O23 - Service: Cliché instantané de volume (VSS) - Unknown owner - C:\WINDOWS\System32\vssvc.exe
O23 - Service: Carte de performance WMI (WmiApSrv) - Unknown owner - C:\WINDOWS\system32\wbem\wmiapsrv.exe
O23 - Service: Service Partage réseau du Lecteur Windows Media (WMPNetworkSvc) - Unknown owner - C:\Program Files\Windows Media Player\WMPNetwk.exe