update: it's not groovymame .. it's hyperspin, or more so hyperlaunch, the scripted kicker it uses. If you disable it, all is well. MAME uses ESC to exit, and for some reason, it doesn't detect the ESC being preset. It finally realizes that the .EXE is no longer running, and it bring HyperSpin back. If you disable it, all is well and fast!