I tried turning on vsync and no dice.
![Sad :(](./images/smilies/icon_sad.gif)
Core 2 duo 3.2 ghz
460GTX 712mb
3gb ram
Windows xp 32bit
Edit: Now it has inexplicably fixed itself. Back to rabbit-fu!
Edit2: Hmm, its back almost as soon as I posted that, on the console it has something about appinputfocus lost and then regained during the lockups.