Ever since I upgraded my early-2011 MBP to ML I've been having intermittent issues with my Mac locking up - the cursor is movable but cannot click or interact with anything on screen. I am also unable to do anything with the keyboard, for example change the backlight brightness. This occurs completely randomly, and I can go a whole day without it happening but I've had it happen twice in the last hour. The most recent one, about 10 minutes ago, looked like this: Note the garbled up area where my dock would be, and also notice the iPhoto hover-over text visible. Usually the dock would be visible rahter than garbled like this, along with that text (which is frozen on the screen, even when I move the cursor away from the dock area). I've tried a clean install, and SMC and PRAM resets but no dice so far. Has anyone had this issue and/or taken it to the genius bar?