I've seen this problem with Windows 2000 and Stisvc.exe around the net
It appears to be a conflict with your camera,scanner, etc..
Just to make sure it's not malicious
Can you do the following please
From my signature below, download and save to a permanent folder Hijackthis 1.99.1
Open Hijackthis.exe
Do a "System Scan and Save logfile"
A text file should open
copy and paste the WHOLE contents of the log here... Don't try and fix anything yet----It is all important
This way we can eliminate malware, if any
My guess is a software problem