[quote=Kaga]
Well no, because turning off the mouse removes all the fun out of it. All they'll notice is that the mouse is missing/broken, and not that none of their icons work. It would be more evil to leave their mouse and watch them try to figure out why they can't click on anything. :P
[/quote]

Yeah, I figured that much out five minutes after posting this; I just forgot to edit the message. Sadly, the prank didn't really work due to the person in question at least knowing something about computers. Now if only I knew the pass of someone else, so that the prank triggers the moment they log in again...

Also, I wanted to simulate a full-system freeze at first. The problem was that the screensaver triggered before the victim came back. Eh, better luck next year.