Have you done some code modifications to try to fix Micromachines' glitches you talked on this other thread?
Delaying the flag does indeed fix the black line (although Battletoads wasnt crashing for me before that so not sure what's happening there exactly.) Now Micro Machines runs without glitches, although that delay definitely needs confirmation.
Looks like other people tried to fix that and had problems with Battletoads:
After testing I discovered that I had managed to break Battletoads and hadn't noticed (probably in a recent round of timing corrections), but I managed to fix it; NMI triggering was off by a CPU cycle which was causing random mayhem.
You should take a look at these.
Sorry for not post the links, but I'm on my crappy cellphone.
Hope you can figure this out!!