Key press on screen change

Hi There

Since changing my main PC to a vista laptop I'm having a strange issue where quite often when moving the cursor from a secondary PC to my main a keypress is sent when I'm not even touching the keyboard.

It appears to happen in all programs ie i'll type a message on msn on secondary PC and move cursor back to main and it will think i'm holding down W or similar.

Has anyone else run into this? I'd rather not have to go back to XP.