Well, a while ago I was having the problem while playing the machine it would go to door open M so I properly by passed the door optics. Has been working for several weeks but now is doing the door open again and if it happens while the reels are spinning I need to press the button on the cpu then turn the reset key. I did an I/O test and found reel 4 doesn't have a 1 value but 0 instead, Don't know if that means anything. Its a 5 reeler 9 nine Triple Stars. Any ideas? The varta battery has been removed. THANKS, John