Doug,

Sounds like a noise problem to me. Try turning the monitor(s) off with the computers on and see if you still have a problem. Most likely, it's the monitor(s).

You can plug the 'problem' device(s) into one of these and it should help: LV6288 Plug In Noise Filter

Try this site:

[Link: smarthomeinc.com]

Hope this helps!

Scott Funk