cpu 100% computer freezes

My PC freezes completely few times a day, when I watch youtube videos in most cases, and then crtl-alt-delete doesn't work. I must restart computer in order for the computer to start working again. I managed to do crtl-alt-delete today and it showed cpu 100%. I was using Mozilla browser, and only two tabs were opened...one of those tabs was youtube.

I use AVG antivirus, I've just finished whole computer scan - no threats were found.

Logfile of Trend Micro HijackThis v2.0.4
Scan saved at 03:45:38, on 10-Dec-12
Platform: Windows XP SP2 (WinNT 5.01.2600)
MSIE: Internet Explorer v8.00 (8.00.6001.18702)
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\nvsvc32.exe
C:\WINDOWS\system32\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\RUNDLL32.EXE
C:\WINDOWS\RTHDCPL.EXE
C:\Program Files\Common Files\Java\Java Update\jusched.exe
C:\Program Files\Messenger\msmsgs.exe
C:\Documents and Settings\sale\Application Data\DRPSu\DrvUpdater.exe
C:\WINDOWS\system32\ctfmon.exe
C:\Program Files\Java\jre7\bin\jqs.exe
C:\Program Files\AVG\AVG2013\avgidsagent.exe
C:\Program Files\AVG\AVG2013\avgwdsvc.exe
C:\Program Files\AVG\AVG2013\avgnsx.exe
C:\Program Files\AVG\AVG2013\avgemcx.exe
C:\Program Files\AVG\AVG2013\avgrsx.exe
C:\Program Files\AVG\AVG2013\avgcsrvx.exe
C:\Program Files\AVG\AVG2013\avgui.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\Program Files\Mozilla Firefox\plugin-container.exe
C:\Documents and Settings\sale\My Documents\Downloads\HijackThis(1).exe

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
O2 - BHO: Java(tm) Plug-In SSV Helper - {761497BB-D6F0-462C-B6EB-D4DAF1D92D43} - C:\Program Files\Java\jre7\bin\ssv.dll
O2 - BHO: Java(tm) Plug-In 2 SSV Helper - {DBC80044-A445-435b-BC74-9C25C1C588A9} - C:\Program Files\Java\jre7\bin\jp2ssv.dll
O4 - HKLM\..\Run: [NvMediaCenter] RUNDLL32.EXE C:\WINDOWS\system32\NvMcTray.dll,NvTaskbarInit
O4 - HKLM\..\Run: [NvCplDaemon] RUNDLL32.EXE C:\WINDOWS\system32\NvCpl.dll,NvStartup
O4 - HKLM\..\Run: [RTHDCPL] RTHDCPL.EXE
O4 - HKLM\..\Run: [WinampAgent] "C:\Program Files\Winamp\winampa.exe"
O4 - HKLM\..\Run: [AdobeAAMUpdater-1.0] "C:\Program Files\Common Files\Adobe\OOBE\PDApp\UWA\UpdaterStartupUtility.exe"
O4 - HKLM\..\Run: [AdobeCS6ServiceManager] "C:\Program Files\Common Files\Adobe\CS6ServiceManager\CS6ServiceManager.exe" -launchedbylogin
O4 - HKLM\..\Run: [SunJavaUpdateSched] "C:\Program Files\Common Files\Java\Java Update\jusched.exe"
O4 - HKLM\..\Run: [AVG_UI] "C:\Program Files\AVG\AVG2013\avgui.exe" /TRAYONLY
O4 - HKCU\..\Run: [MSMSGS] "C:\Program Files\Messenger\msmsgs.exe" /background
O4 - HKCU\..\Run: [DrvUpdater] C:\Documents and Settings\sale\Application Data\DRPSu\DrvUpdater.exe /hide
O4 - HKCU\..\Run: [ctfmon.exe] C:\WINDOWS\system32\ctfmon.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
O22 - SharedTaskScheduler: Browseui preloader - {438755C2-A8BA-11D1-B96B-00A0C90312E1} - C:\WINDOWS\system32\browseui.dll
O22 - SharedTaskScheduler: Component Categories cache daemon - {8C7461EF-2B13-11d2-BE35-3078302C2030} - C:\WINDOWS\system32\browseui.dll
O23 - Service: Adobe Flash Player Update Service (AdobeFlashPlayerUpdateSvc) - Adobe Systems Incorporated - C:\WINDOWS\system32\Macromed\Flash\FlashPlayerUpdateService.exe
O23 - Service: AVGIDSAgent - AVG Technologies CZ, s.r.o. - C:\Program Files\AVG\AVG2013\avgidsagent.exe
O23 - Service: AVG WatchDog (avgwd) - AVG Technologies CZ, s.r.o. - C:\Program Files\AVG\AVG2013\avgwdsvc.exe
O23 - Service: Google Update Service (gupdate) (gupdate) - Google Inc. - C:\Program Files\Google\Update\GoogleUpdate.exe
O23 - Service: Google Update Service (gupdatem) (gupdatem) - Google Inc. - C:\Program Files\Google\Update\GoogleUpdate.exe
O23 - Service: Java Quick Starter (JavaQuickStarterService) - Oracle Corporation - C:\Program Files\Java\jre7\bin\jqs.exe
O23 - Service: Mozilla Maintenance Service (MozillaMaintenance) - Mozilla Foundation - C:\Program Files\Mozilla Maintenance Service\maintenanceservice.exe
O23 - Service: NVIDIA Display Driver Service (nvsvc) - NVIDIA Corporation - C:\WINDOWS\system32\nvsvc32.exe

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