Key combinations causing GameEX+MAME to lockup

[Sir Auros]

I have no idea how to search for this problem, especially since I can barely describe it, but playing a few four-player games tonight using GameEX, and ipac4, and mame 117, we had the picture blink out. We were unable to restore the picture without exiting, but the game continued anyway.

At first, it was the stupid StickyKeys thing, and I disabled that; however, a few games later the screen blinked and I had to kit escape again. No dialog box or anything.

Any general tips for disabling the shortcut keys or whatever might be causing GameEX to flip out? The only changes I've made to the ipac programming were swapping the L key for T, since GameEX uses L for that controller map.