Back in May I started having a problem with one of my cashiers not taking credit cards. It wouldn't even beep to acklnowledge a card had been swiped. I would power the ACW down then unplug the CC power pack and that would take care of it for awhile. Hamilton told me the next time it happened to just power down the ACW and see if that took care of it. That is what I did and it did take care of it for awhile. They said the problem would be in the controller since powering down the ACW brought it back to life. I sent it in and they couldn't get it to act up but I had them replace any parts that could possibley be causing the problem. Received it back and thought all was OK but it started again. Mean time I sent in an older controller and had it re-programed to take CC. When it came back I installed it and thought everything was OK until today. The newly re-programed controler is doing the same thing. I shut the power to the ACW off and all is OK. The problem is very sporadic. This last time it had taken a whole week before it showed up again. Now approxamately $330.00 later I still have the problem. I checked harnesses and any other connections that I thought it could possible be. Hamilton said if what they repiared on the first one didn't fix it that I should get a new controller. (approx $1,000) I haven't talked to them yet as to having the same problem with the second controller. It seems to me that since they could not get it to malfunction at Hamilton and is happening with two repaired controllers that just maybe the problem isn't in the controller. DOES ANYONE OUT THERE HAVE ANY IDEAS as to what is causing this???????????