Blocage du pc pendant 30sec aléatoirement

Bonjour,

Depuis pas mal de temps j'ai mon pc qui se bloque pendant 20sec environ de façon aléatoire et pendant ce temps tout est bloqué. Ca le faisait essentiellement sur msn messenger.
Je viens de passer à XP service pack 2 en pensant que ça allait améliorer les choses et là c'est pire. Il se bloque très souvent sur firefox alors qu'avant je n'avais pas ce pb. Sur Opéra je n'ai pas le pb.
Voici ma log Hijackthis.

Merci pour votre aide.

Logfile of Trend Micro HijackThis v2.0.2
Scan saved at 04:28:57, on 10/03/2009
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v6.00 SP2 (6.00.2900.2180)
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\Ati2evxx.exe
C:\WINDOWS\Explorer.EXE
C:\Program Files\Lavasoft\Ad-Aware\aawservice.exe
C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
C:\Program Files\Alwil Software\Avast4\ashServ.exe
C:\Program Files\ATI Technologies\ATI.ACE\cli.exe
C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
C:\Program Files\Java\jre6\bin\jusched.exe
C:\WINDOWS\system32\spoolsv.exe
G:\Program Files\nokia\Nokia PC Suite 6\LaunchApplication.exe
C:\WINDOWS\RTHDCPL.EXE
C:\Program Files\Fichiers communs\Real\Update_OB\realsched.exe
H:\Program Files\Winamp\winampa.exe
C:\Program Files\Skype\Phone\Skype.exe
C:\Program Files\Fichiers communs\Ahead\lib\NMBgMonitor.exe
C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
C:\Program Files\Avira\AntiVir PersonalEdition Classic\sched.exe
C:\Program Files\ATI Technologies\ATI.ACE\CLI.exe
C:\Program Files\Avira\AntiVir PersonalEdition Classic\avguard.exe
C:\Program Files\MSI\DigiCell\DigiCell.exe
C:\Program Files\e-Carte Bleue LCL\ecbl-lcl.exe
C:\Program Files\MSI\PC Alert 4\PCAlert4.exe
C:\Program Files\Java\jre6\bin\jqs.exe
C:\WINDOWS\System32\svchost.exe
C:\Program Files\Alwil Software\Avast4\ashMaiSv.exe
C:\Program Files\Alwil Software\Avast4\ashWebSv.exe
C:\Program Files\PC Connectivity Solution\ServiceLayer.exe
C:\WINDOWS\System32\wbem\wmiapsrv.exe
C:\Program Files\ATI Technologies\ATI.ACE\cli.exe
C:\WINDOWS\system32\wuauclt.exe
C:\Program Files\Avira\AntiVir PersonalEdition Classic\avgnt.exe
C:\Program Files\MSN Messenger\msnmsgr.exe
c:\syz_dat\systray.exe
C:\Program Files\MSN Messenger\usnsvc.exe
C:\Program Files\Opera\opera.exe
H:\temp\HijackThis.exe

R1 - HKCU\Software\Microsoft\Internet Explorer\Main,Search Bar = https://www.bing.com/?cc=fr&toHttps=1&redig=D4322FEE7CF74A348CB9CE970F098EF5
R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = https://www.msn.com/fr-fr
R1 - HKLM\Software\Microsoft\Internet Explorer\Main,Default_Page_URL = https://fr.yahoo.com/
R0 - HKLM\Software\Microsoft\Internet Explorer\Main,Start Page = https://fr.yahoo.com/
R0 - HKCU\Software\Microsoft\Internet Explorer\Toolbar,LinksFolderName = Liens
R3 - URLSearchHook: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn1\yt.dll
O2 - BHO: &Yahoo! Toolbar Helper - {02478D38-C3F9-4EFB-9B51-7695ECA05670} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn1\yt.dll
O2 - BHO: Adobe PDF Reader Link Helper - {06849E9F-C8D7-4D59-B87D-784B7D6BE0B3} - C:\Program Files\Fichiers communs\Adobe\Acrobat\ActiveX\AcroIEHelper.dll
O2 - BHO: Winamp Toolbar Loader - {25CEE8EC-5730-41bc-8B58-22DDC8AB8C20} - C:\Program Files\Winamp Toolbar\winamptb.dll
O2 - BHO: e-Carte Bleue Browser Helper Object - {2E03C0FD-4C48-43A7-9A54-00240C70FF16} - C:\WINDOWS\System32\BhoECart.dll
O2 - BHO: Spybot-S&D IE Protection - {53707962-6F74-2D53-2644-206D7942484F} - C:\Program Files\Spybot - Search & Destroy\SDHelper.dll
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre6\bin\ssv.dll
O2 - BHO: (no name) - {7E853D72-626A-48EC-A868-BA8D5E23E045} - (no file)
O2 - BHO: Windows Live Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Fichiers communs\Microsoft Shared\Windows Live\WindowsLiveLogin.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: Yahoo! Toolbar - {EF99BD32-C1FB-11D2-892F-0090271D4F88} - C:\PROGRA~1\Yahoo!\Companion\Installs\cpn1\yt.dll
O3 - Toolbar: Winamp Toolbar - {EBF2BA02-9094-4c5a-858B-BB198F3D8DE2} - C:\Program Files\Winamp Toolbar\winamptb.dll
O4 - HKLM\..\Run: [ATICCC] "C:\Program Files\ATI Technologies\ATI.ACE\cli.exe" runtime
O4 - HKLM\..\Run: [High Definition Audio Property Page Shortcut] HDAShCut.exe
O4 - HKLM\..\Run: [WebCam Go Plus Sti Service Application] Wcgopsvc
O4 - HKLM\..\Run: [avast!] C:\PROGRA~1\ALWILS~1\Avast4\ashDisp.exe
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Java\jre6\bin\jusched.exe"
O4 - HKLM\..\Run: [NeroFilterCheck] C:\WINDOWS\System32\NeroCheck.exe
O4 - HKLM\..\Run: [PCSuiteTrayApplication] G:\Program Files\nokia\Nokia PC Suite 6\LaunchApplication.exe -startup
O4 - HKLM\..\Run: [Adobe Reader Speed Launcher] "C:\Program Files\Adobe\Reader 8.0\Reader\Reader_sl.exe"
O4 - HKLM\..\Run: [RTHDCPL] RTHDCPL.EXE
O4 - HKLM\..\Run: [Alcmtr] ALCMTR.EXE
O4 - HKLM\..\Run: [TkBellExe] "C:\Program Files\Fichiers communs\Real\Update_OB\realsched.exe" -osboot
O4 - HKLM\..\Run: [WinampAgent] "h:\Program Files\Winamp\winampa.exe"
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\Avira\AntiVir PersonalEdition Classic\avgnt.exe" /min
O4 - HKCU\..\Run: [Skype] "C:\Program Files\Skype\Phone\Skype.exe" /nosplash /minimized
O4 - HKCU\..\Run: [BgMonitor_{79662E04-7C6C-4d9f-84C7-88D8A56B10AA}] "C:\Program Files\Fichiers communs\Ahead\lib\NMBgMonitor.exe"
O4 - HKCU\..\Run: [SpybotSD TeaTimer] C:\Program Files\Spybot - Search & Destroy\TeaTimer.exe
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 - Global Startup: ATI CATALYST System Tray.lnk = C:\Program Files\ATI Technologies\ATI.ACE\CLI.exe
O4 - Global Startup: DigiCell.lnk = C:\Program Files\MSI\DigiCell\DigiCell.exe
O4 - Global Startup: e-Carte Bleue LCL.lnk = C:\Program Files\e-Carte Bleue LCL\ecbl-lcl.exe
O4 - Global Startup: Microsoft Office.lnk = C:\Program Files\Microsoft Office\Office10\OSA.EXE
O4 - Global Startup: PC Alert 4.lnk = C:\Program Files\MSI\PC Alert 4\PCAlert4.exe
O8 - Extra context menu item: &Clean Traces - C:\Program Files\DAP\Privacy Package\dapcleanerie.htm
O8 - Extra context menu item: &Download with &DAP - C:\Program Files\DAP\dapextie.htm
O8 - Extra context menu item: &Winamp Search - C:\Documents and Settings\All Users\Application Data\Winamp Toolbar\ieToolbar\resources\en-US\local\search.html
O8 - Extra context menu item: Download &all with DAP - C:\Program Files\DAP\dapextie2.htm
O8 - Extra context menu item: E&xport to Microsoft Excel - res://C:\PROGRA~1\MICROS~2\Office10\EXCEL.EXE/3000
O9 - Extra button: Messenger - {4528BBE0-4E08-11D5-AD55-00010333D0AD} - C:\PROGRA~1\Yahoo!\Common\yhexbmesfr.dll
O9 - Extra 'Tools' menuitem: Yahoo! Messenger - {4528BBE0-4E08-11D5-AD55-00010333D0AD} - C:\PROGRA~1\Yahoo!\Common\yhexbmesfr.dll
O9 - Extra button: (no name) - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\Program Files\Spybot - Search & Destroy\SDHelper.dll
O9 - Extra 'Tools' menuitem: Spybot - Search && Destroy Configuration - {DFB852A3-47F8-48C4-A200-58CAB36FD2A2} - C:\Program Files\Spybot - Search & Destroy\SDHelper.dll
O9 - Extra button: Messenger Backup - {ECC5777A-6E88-BFCE-13CE-81F134789E7B} - C:\Program Files\Messenger Backup\Messenger Backup (file missing)
O9 - Extra 'Tools' menuitem: &Messenger Backup - {ECC5777A-6E88-BFCE-13CE-81F134789E7B} - C:\Program Files\Messenger Backup\Messenger Backup (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: {56336BCB-3D8A-11D6-A00B-0050DA18DE71} - http://software-dl.real.com/105c82f195cda32f4f01/netzip/RdxIE601_fr.cab
O23 - Service: Lavasoft Ad-Aware Service (aawservice) - Lavasoft - C:\Program Files\Lavasoft\Ad-Aware\aawservice.exe
O23 - Service: Planificateur Avira AntiVir Personal - Free Antivirus (AntiVirScheduler) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Classic\sched.exe
O23 - Service: Avira AntiVir Personal - Free Antivirus Guard (AntiVirService) - Avira GmbH - C:\Program Files\Avira\AntiVir PersonalEdition Classic\avguard.exe
O23 - Service: avast! iAVS4 Control Service (aswUpdSv) - ALWIL Software - C:\Program Files\Alwil Software\Avast4\aswUpdSv.exe
O23 - Service: Ati HotKey Poller - ATI Technologies Inc. - C:\WINDOWS\System32\Ati2evxx.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: InstallDriver Table Manager (IDriverT) - Macrovision Corporation - C:\Program Files\Fichiers communs\InstallShield\Driver\11\Intel 32\IDriverT.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Sun Microsystems, Inc. - C:\Program Files\Java\jre6\bin\jqs.exe
O23 - Service: Sunbelt Kerio Personal Firewall 4 (KPF4) - Sunbelt Software - C:\Program Files\Sunbelt Software\Personal Firewall\kpf4ss.exe
O23 - Service: Remote Packet Capture Protocol v.0 (experimental) (rpcapd) - NetGroup - Politecnico di Torino - C:\Program Files\WinPcap\rpcapd.exe
O23 - Service: ServiceLayer - Nokia. - C:\Program Files\PC Connectivity Solution\ServiceLayer.exe