it's CMOS corruption. take out the batteries, wait about 10 minutes, turn the game on. you'll get the factory settings restored message then. now go into the settings screen and manually reset factory settings, bookkeeping totals, and high score table. (enter settings by pressing the Advance button, and using Advance to cycle between the screens)
now wait for the operator message screen to come up, it should just be ---------- now. if not, repeat the factory restore procedure I mentioned a few times. once that's wiped out, power the game off and put the batteries back in.
you'll have to factory restore once more then. it's a stupid process, but there was some kind of issue with how Sinistar's code handles the CMOS. it happens to it the most of all the games I guess.