up arrow key wierdness

My up arrow key has been hijacked by something. It works but most of the time it does two things at once. First it beeps if pressed in the finder, in Safari it works normally, in other programs like Illustrator it changes the pallets as well as moves an object. In iTunes it beeps and moves up the list. Same thing in Mail. Sounds like some program has hijacked it for a short cut but I don't use key modifiers as a rule. I've restored defaults in keyboard preferences to no avail. Any ideas?