CTRL key causes keyboard malfunction

This is sort of a difficult problem to explain, but here
goes.
For some reason, when I use my CTRL key when I'm
operating Word, my keyboard seems to get all jumbled.
None of the letter match up with my keystrokes. Sometimes
it happens if I've hit CTRL once, sometimes I'll have
used it multiple times before the problem starts.
Any clue what's happening or, more importantly, how I can
get it to stop? I'm a big fan of quick keys and write for
a living, this problem is driving me nuts!
Please help.