Can you be more specific about the issue you are facing with?
How long have been facing this? Was it after bringing any changes in your machine (eg: Installing any 3rd party softwares)?
Primarily scan your machine with Avast free addition in safe mode. And then with Malwarebytes application (Still in safe mode)
PS: All the way I was wondering to know.. why are you still using Windows 2000. Why don't you upgrade it to WIndows XP, Vista or 7?
Thank you :)