Mac semi crash, nothing responding OSX lion 10.7.3

So I'm playing mine craft and it crashes for some weird reason then this box comes up like normal with the ignore report now I can't click anything well I can but the box for that program doesn't come up and I can't click the apple I con it just has the rainbow loading icon I. Can press f3 & 4 used load new screens but can't click anything and the only predominant thing in the screen is the error report and I can't click tat either and I can't restart cause im rendering a video

Sorry to suggest it, but I suspect your only way is to restart the Mac, either by the usual way (if it will let you), or by pushing & holding-in the "Start" button on the back of the Mac.