i've done that, well in mamewah i have a button set to extra options 1 and the resolution is 800x600 (i use that for all the ones i have probs with)
BUT
they still don't go 800X600 it's like the screen is just smaller, and i run it at 800X600 and it gets bigger, but still doesn't fill the screen how it should
they also run slower when i change the resolution, but when i let it run in the smaller screen they run 100%
andn it's def not a problem since i havent had this beforeand the pc is well above mame spec, i can almost run mk3 full speed

lol i'm not sure why it does this...