I didn't wire ground from batteries to reg, and had 7.4 from the batteries directly to the 7805 with a wire connected to that going to the reg....what were you wiring to the regulator before?
The reg. Was originally connected ton the n64's ground. I read somewhere that you should connect it straight to the batterys ground.I really don't know how to explain this to someone that doesn't understand it, but in electrical circuits you always* need to connect a voltage and a ground.