I have a series 2 Tivo DVR, Model Number TCD 540040 (that's what it says on the unit, I'm not sure if that's important). I have a digital cable box: Motorola DCT2500. I have had the Tivo for over a year and have had no problems. I use the serial connector. All of a sudden the other day when I hit channel Up, and the info window comes up with the higher channel, but the channel doesn't actually change. In other words, the Tivo thinks it changed the channel, but it didn't. I restarted the Tivo, I powercycled. I powercycled the cable box, and everything else around it. I verified that all cables are snugly plugged in. Help! What could be going wrong?