Comma key is unusable on my machine

I have been using RH 7.2 for some time now and have just moved to 7.3 on
several machines. On my machine at home, and only there, when I juse
the "," key (either shifted or not) the effect is a backspace.

If X is not running, the comma key works as advertised. Does anyone
have a clue as to what might be remapping the key or where I should look?

Stephen