Arcade Cards are notorious for this problem, especially if you are playing them through a region adapter. In 99% of cases like this, the cart isn't seated correctly or has a dirty pin, like Steve mentioned.
I'm not sure why ACs are more prone to this problem than, say, the System 3.0 cards but they do seem to be.
Also, you probably couldn't find a ROM of the AC because the AC isn't just a ROM. It's also a bank of RAM. You can't emulate a bank of RAM (a physical piece of hardware) with a simple ROM image.