Weird Keystroke Combination Problem...

So lately, my Core Duo MacBook has decided it doesn't like the keystroke combos for copy and select all. The Apple key and the c and a keys work fine by themselves, as do all other Command-"x" keystrokes like paste, quit, etc. But for some reason I can't select all or copy a selection with a keystroke.

Has anyone else experienced this and learned of a solution or heard of one? Not sure what's happening, but its definitely brought to late how often I use those keystrokes!

thx.

EDIT:

Nevermind. I just realized that I had assigned those combos as triggers for Quicksilver, not thinking that that would be a conflict. And of course, they weren't working because I don't think QS or Leopard wants to share key combos. I changed that and resarted QS and all was good. Sorry for the wasted post, but it did seem to trigger my memory!