MAME 141 won't run games in full screen.

For some reason, MAME 141 will not run games in full screen for me. I have made sure that the "run in window" box is not checked. Even more bizarre is that Galaga runs full, while everything else runs in a window. Any recommendations how to fix this?

Try deleting the file default.cfg in your mame folder. Then when you run a game mame will generate a fresh one. Often the quickest way to fix a weird config related anomaly.