Hi macray, to shut down a program that's gone all wonky hold down the Alt key and then when you've got Alt held down when you right-click on the dock icon there will be "Force quit" option that you can use to forcibly shut it down.

Then you'll need to update to the latest version, MoI was having problems with some changes in the new OSX 10.7.5 and 10.8.2 updates, and if you're still using an older version of MoI with these latest OSX versions it won't work properly, so you'll need to get the latest 2.52 MoI version from here: http://moi3d.com/reinstall.htm

- Michael