keyboard problem

Over the years I've had this problem occasionally on different computers and operating systems and it's happend a couple of times this past week on my P4 2.2 system with Win XP Home.

For some reason the CAPS LOCK / SHIFT keys seems to get screwed up. With SHIFT or CAPS LOCK off I'll get upper case on all my keys, and with them ON I'll get lower case. The number keys at the top of the keyboard seem to get stuck completely on the symbols no matter what I do with the CAPS LOCK or the SHIFT key. A reboot always fixes the problem.

Is it possible I'm accidently hitting some specific key combination that causes this...or is it something else? Anyone else ever experience this problem?

Thanks,
BH Davis