SVCHOST.exe taking up 100% of my processor for upto 20mins on start up.WHY??? HELP!!!!!?

hijack scan...Logfile of HijackThis v1.97.7

Scan saved at 19:03:33, on 20/09/2006

Platform: Windows XP SP1 (WinNT 5.01.2600)

MSIE: Internet Explorer v6.00 SP1 (6.00.2800.1106)

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:\Program Files\Common Files\Symantec Shared\ccSetMgr.exe

C:\Program Files\Norton Personal Firewall\NISUM.EXE

C:\Program Files\Common Files\Symantec Shared\SPBBC\SPBBCSvc.exe

C:\Program Files\Common Files\Symantec Shared\ccEvtMgr.exe

C:\WINDOWS\system32\LEXBCES.EXE

C:\WINDOWS\system32\spoolsv.exe

C:\WINDOWS\system32\LEXPPS.EXE

C:\Program Files\Symantec\LiveUpdate\ALUSchedulerSv...

C:\Program Files\Norton Personal Firewall\ccPxySvc.exe

C:\WINDOWS\system32\crypserv.exe

C:\Program Files\Norton AntiVirus\navapsvc.exe

C:\WINDOWS\system32\Ati2evxx.exe

C:\WINDOWS\Explorer.EXE

C:\Program Files\Norton AntiVirus\AdvTools\NPROTECT.EXE

C:\WINDOWS\System32\svchost.exe

C:\WINDOWS\System32\LXSUPMON.EXE

C:\Program Files\Common Files\Symantec Shared\ccApp.exe

C:\Program Files\ATI Technologies\ATI Control Panel\atiptaxx.exe

C:\Program Files\Common Files\Symantec Shared\Security Center\UsrPrmpt.exe