I just switched from PC to Mac, and there's a problem with Photoshop on OS X: I can't move any layer with the Move tool. It doesn't display any error or dialog box but it simply won't do it. Whenever I drag a layer, it will move back to its original location. However, I can nudge it using the arrow keys.
Mac OS X Lion 10.7.2
Photoshop CS 5.5