I decided -- probably stupidly -- to replace my two cards per S3 with one M Card in each unit. The initial swap went fine. Popped the olds cards out, installed one M Card in each, called the cable company, activated them -- everything was just great. I didn't even have to re-run guided setup. Both S3s had dual tuners active. It was all good. I then got a message saying I had to re-run guided setup. So I did. And once I did that, I now have one cablecard (albeit an M-Card) and only one active tuner per unit. The second tuner has flat-out disappeared. Here are my questions: 1. Am I doing something wrong, or is the M-Card just not supported on an S3? 2. If not formally supported, is there a workaround to get dual tuners working? Or, do I need to reinstall the original cablecards? 3. Alternatively, can I have two M-Cards installed in a single S3, one in each cablecard slot? 4. Or, can I install one of the old cards into slot 2, leaving the M-Cards installed in slot 1 on each unit? Thanks.