Windows Vista Windows switching - with no key press!

Hey everyone. I've been searching the web all day and I have yet to find an answer, or even a similar problem.

So far, I'm not very excited with Vista. It doesn't run anything, and what it does run, you need to buy updates to get it to work. Here's a new problem: My boss's computer is running Vista Business. He will be randomly working on whatever, and all of a sudden that window reverts to the background and something else comes up. It's like the computer's having a seizure and forgot what it's doing. He doesn't use the keyboard that often except for typing, and all of the problems happen when he's clicking around on a lot of things.

What the heck? Any ideas, suggestions, acrimonious shouts of joy?