I've got an iMac running Mac OS X 10.5.8 that is ignoring a few key combinations (most of the time, that is). Left-shift-e and left-command-c have stopped working. It's not the physical keys as, for example, left-shift-d works just fine. I can type E or copy using the right-hand shift and command keys.
Sometimes, and I think it's when I'm catching my computer unawares (while it's processing), left-command-c works just fine.
Is there a corrupted preference file hanging around somewhere?