Automatic Updates is likely to blame for this. Check in task manager
/ sort by CPU usage - do you see svhost.exe hogging the cycles?
1. Download & install the Windows Update Agent 3 from
http://support.microsoft.com/kb/926464.
2. Download & install the KB927891 fix (reinstall it if you had
previously
done so)
3. Re-set Windows Update & delete the cache, in a command line....
net stop wuauserv
del /f /s /q %windir%\SoftwareDistribution\*.*
net start wuauserv
wuauclt.exe /detectnow
4. Then reboot and run WU/Microsoft Update and make sure everything
is fully
patched.
You may see a couple of residual svchost.exe errors (check the
date/timestamps; they are probably old) but this should do it.