Possible Virus? Has anyone seen this?

I have 6 Windows 2000 Pro pc’s with service pack 2 and some with Service pack 3. When the pc’s boot up you are able to login but that is it, I never get to the desktop just an hour glass. If you are lucky enough to get to the desktop things happen such as, when you open task list it opens then closes instantly. We are running Symantec Corp. Edition 8.1 and that also is not working either, and I noticed the service for Symantec is not turned on, whenyou try to manually turn it on I recieve an error that it can not start. Do I have a virus of some sort? Just a note the pc’s do come up in safe mode but Symantec still will not run.

Thanks,

Bobby