keyboard

Twice now, my keyboard has started 'typing' random letters instead of what I type. I type The and screen will show Ugr or some such. This only happened, so far, when emailing in T-Bird. Hasn't happened in blogs or posts. I reboot and all is well.
Is there something else besides rebooting to solve the random connections? Keyboard isn't new, have used it for 6+ months and it was used then. But nary a problem 'til now. Any ideas? Thanks.
Using XP.

 

First thing I'd try is to boot in safe mode with networking and see what happens there. Then try another keyboard. A new generic keyboard is only like $10 at just about any PC shop....