I have also had issues when the card gets swiped 3x. My MC transactions frequently get "card not accepted" issues, and I think it's because I'm swiping the card too many times. I also find the regular checkers can load the BB, no problem, when Kate is broken or the MC line is long. I've had much better results at the checkout line than the money center. I've tried the uber-fast "hit the cancel button" trick, but, basically, the MC bombs out for me more often than not.