For some weird reason, when I opened GT Lite to play COD 4 today, it took my screen size down from full size to about 1/4th the size. It stays that way whether I open the game or go through GT Lite. I have an IMac. Any suggestions?

This is probably in the COD4 ingame options somewhere. Make sure that the resolution chosen in the game matches that of your regular desktop screen resolution.

Tried that but it makes the computer run way too slow. Also I am still on my desktop when I do that. before, when I log on, the program takes the whole computer screen. Runs fast.
There was some window open when I clicked on Join this Server, GT Lite came on, I clicked the window to get rid of it, then the screen shrunk. Too weird, but definately a setting issue.

Thanks for the response.