PC locks up 10 minutes into windows start up

[T-Rex]

Computer boots fine , i get into windows , i run a few programs , firefox , xfire , and all of a sudden the computer locks , nothing works mouse wont move screen just freezes , i stay clear of malware sites usually , i have to keep this brief because it will lock up again soon , ive got a hijackthis log on here.

Logfile of Trend Micro HijackThis v2.0.3 (BETA)
Scan saved at 1:28:03 PM, on 12/10/2009
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\svchost.exe
C:\WINDOWS\System32\svchost.exe
C:\WINDOWS\system32\spoolsv.exe
C:\Program Files\Avira\AntiVir Desktop\sched.exe
C:\Program Files\Avira\AntiVir Desktop\avguard.exe
C:\WINDOWS\system32\PnkBstrA.exe
C:\WINDOWS\system32\PnkBstrB.exe
C:\WINDOWS\System32\PAStiSvc.exe
C:\WINDOWS\Explorer.EXE
C:\WINDOWS\system32\wscntfy.exe
C:\WINDOWS\RTHDCPL.EXE
C:\Program Files\Thomson\SpeedTouch USB\Dragdiag.exe
C:\Program Files\Avira\AntiVir Desktop\avgnt.exe
C:\Program Files\Windows Live\Messenger\msnmsgr.exe
C:\Program Files\TrojanHunter 5.0\TrojanHunter.exe
C:\Program Files\ATI Technologies\ATI.ACE\Core-Static\MOM.exe
C:\Program Files\ATI Technologies\ATI.ACE\Core-Static\ccc.exe
C:\Program Files\Mozilla Firefox\firefox.exe
C:\WINDOWS\system32\msiexec.exe
C:\Program Files\TrendMicro\HiJackThis\HiJackThis.exe

R0 - HKCU\Software\Microsoft\Internet Explorer\Main,Start Page = http://uk.ask.com?o=15153&l=dis
O2 - BHO: AcroIEHelperStub - {18DF081C-E8AD-4283-A596-FA578C2EBDC3} - C:\Program Files\Common Files\Adobe\Acrobat\ActiveX\AcroIEHelperShim.dll
O2 - BHO: (no name) - {5C255C8A-E604-49b4-9D64-90988571CECB} - (no file)
O2 - BHO: Windows Live Sign-in Helper - {9030D464-4C02-4ABF-8ECC-5164760863C6} - C:\Program Files\Common Files\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
O4 - HKLM\..\Run: [RTHDCPL] RTHDCPL.EXE
O4 - HKLM\..\Run: [SpeedTouch USB Diagnostics] "C:\Program Files\Thomson\SpeedTouch USB\Dragdiag.exe" /icon
O4 - HKLM\..\Run: [StartCCC] "C:\Program Files\ATI Technologies\ATI.ACE\Core-Static\CLIStart.exe" MSRun
O4 - HKLM\..\Run: [avgnt] "C:\Program Files\Avira\AntiVir Desktop\avgnt.exe" /min
O4 - HKLM\..\Run: [THGuard] "C:\Program Files\TrojanHunter 5.0\THGuard.exe"
O4 - HKCU\..\Run: [msnmsgr] "C:\Program Files\Windows Live\Messenger\msnmsgr.exe" /background
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: {20A60F0D-9AFA-4515-A0FD-83BD84642501} (Checkers Class) - http://messenger.zone.msn.com/binary/msgrchkr.cab56986.cab
O16 - DPF: {6414512B-B978-451D-A0D8-FCFDF33E833C} (WUWebControl Class) - http://update.microsoft.com/windowsupdate/v6/V5Controls/en/x86/client/wuweb_site.cab?1256946444468
O16 - DPF: {6E32070A-766D-4EE6-879C-DC1FA91D2FC3} (MUWebControl Class) - http://www.update.microsoft.com/microsoftupdate/v6/V5Controls/en/x86/client/muweb_site.cab?1258141476984
O16 - DPF: {C3F79A2B-B9B4-4A66-B012-3EE46475B072} (MessengerStatsClient Class) - http://messenger.zone.msn.com/binary/MessengerStatsPAClient.cab56907.cab
O17 - HKLM\System\CCS\Services\Tcpip\..\{93DD833B-DFDB-4207-AB05-94E57446BE90}: NameServer = 212.139.132.21 212.139.132.20
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: Avira AntiVir Scheduler (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: PEVSystemStart - Unknown owner - C:\ComboFix\PEV.cfxxe
O23 - Service: PnkBstrA - Unknown owner - C:\WINDOWS\system32\PnkBstrA.exe
O23 - Service: PnkBstrB - Unknown owner - C:\WINDOWS\system32\PnkBstrB.exe
O23 - Service: STI Simulator - Unknown owner - C:\WINDOWS\System32\PAStiSvc.exe

--
End of file - 4309 bytes

[T-Rex]

I just about managed to run combo fix , and it explained it found root-kit detection, and it rebooted my pc and it came up with this.

Stealth MBR rootkit/Mebroot/Sinowal detector 0.3.7 by Gmer, http://www.gmer.net

device: opened successfully
user: MBR read successfully
called modules: ntkrnlpa.exe catchme.sys CLASSPNP.SYS disk.sys >>UNKNOWN [0x895C5430]<<
kernel: MBR read successfully
detected MBR rootkit hooks:
\Driver\Disk -> CLASSPNP.SYS @ 0xba0ecfc3
\Driver\ACPI -> 0x895c5430
\Driver\atapi -> atapi.sys @ 0xb9f117b4
IoDeviceObjectType -> DeleteProcedure -> ntkrnlpa.exe @ 0x8058241c
 ParseProcedure -> ntkrnlpa.exe @ 0x8058155c
\Device\Harddisk0\DR0 -> DeleteProcedure -> ntkrnlpa.exe @ 0x8058241c
 ParseProcedure -> ntkrnlpa.exe @ 0x8058155c
NDIS:  -> SendCompleteHandler -> 0x0
 PacketIndicateHandler -> 0x0
 SendHandler -> 0x0
Warning: possible MBR rootkit infection !
copy of MBR has been found in sector 0x012A14C00
malicious code @ sector 0x012A14C03 !
PE file found in sector at 0x012A14C19 !
MBR rootkit infection detected ! Use: "mbr.exe -f" to fix.

[harry 48]

http://www.computerhope.com/forum/index.php/topic,46313.0.html

go to above and complete post the other 2 logs here and an expert will look at them , harry