Quoted from Prmailers:
Replace the 40 pin interconnect on the driver board - this is a must if not done already.
Also, replacing the sockets for the game ROMS can clear up random anomalies.
He got a new Rottendog combo board. No more 40 pin. I'm guessing a reset issue due to a intermittent loss of the 5v from the p/s. Check to see if you're getting the 5v on the new combo board. If voltage is low, start with connectors for solid connection, too loose, burnt, will cause a loss. Then move to the p/s. Look for cracked solder joints on the back of the male pins. If issue is still not fixed move to replacing the four filter caps and the 5v regulator on the p/s.