Mail won't quit
On occasion (I've been unable to find a pattern.) Mail can't be quit. Quit is grayed out and Mail in the dock Quit doesn't work. I click Finder in the dock to no effect. The only way to shut the machine down is to hold the power button down. What gives?
MacBook Pro, OS X Mountain Lion (10.8.2), 250G, 500G, 1T Ext HDs; CS 5