Stopped booting games. About one in fifty times it'll boot the game, otherwise it either wont load anything or it will read the game disc as a DVD (getting that weak 'put this disc in an XBOX 360 console').
Those odds are just good enough that I'll waste half an hour trying to get Call of Duty 4 to load when I feel like playing Free-For-All. Like a bad lawn mower eventually it'll start up, and then it's fine, but it's still ridiculously frustrating.
It's a good thing it's still under warranty, otherwise I'd be really ticked. At least I've got my Wii sitting there with some new games to play while it's off getting repaired. Samus Aran has saved my butt again.