My friend has a pc that has a CD rom tray that keeps opening/closing on its own. OS=W2Kpro

I ran trend virus and found no virus
I installed/ran spybot cleaned out known problems
cleaned out the .tmp files
restarted pc

we installed anther cd rom in its place and this is doing the same thing.
I can put a CD in the tray and it works and then the opening/clsoing stops.

Does this sound like a virus or what?
Thanks