Brilliant work!
Quick item: As the game starts and transitions off your startup screen, the emulator is minimized. Not entirely, but it's a smaller window than full screen, and it forces me to maximize. Even when I maximize, playing the next game (or even the same one) will start minimized again. This was observed with every system except Dreamcast, strangely enough.
Hope this helps, or if anyone has ideas. Cheers!