Strange Problem with keypresses on Win32

[exits funnel]

Hello,

I've been using the native windows Emacs (21.3.1) one Win2000 for 
several months and there has been one intermittently recurring problem. 
 Every once in a while, I encounter a situation where the key I press 
and the letter which appears on the screen aren't the same.  For 
instance, I might press the 'a' key and see a 'q' or I might press the 
'z' key and see a 'w'. I'm not sure if the same keys are affected each 
time or even if the 'replacement' letters are the same.  The only 
solution I've found is to shutdown Emacs altogether and restart it. 
This can be more than a bit annoying if I have a lot of buffers open or 
if I'm in the middle of, for instance, a debugging session.  Has anyone 
else experienced this or know what the problem is?  Is there some 
solution short of restarting Emacs?  Thanks in advance for any help 
anyone can offer.

-exits