The machine had an unused Ethernet port. We disabled that and the problem went away.
When I'm typing along, suddenly my cursor hangs up. It stays in the samp spot and nothing goes on the screen. Even pressing the arrow keys (left, right, up down)can't unstick the cursor. Then after about two minutes (or longer), the cursor jumps ahead and puts on the screen what I was typing. This happens about every ten minutes. Doesn't matter what program I'm in--Word, Excel, Outlook, on the Internet. It's driving me nuts.