I'm sorry to hear that you're having this problem.
How did you connect both televisions? With HDMI, or component cables?
Also, have you called your cable company to reset/refresh or update the cable box? Often times, updates are available that address these concerns.
Keep me posted.
I have a two month old Samsung LN40B750 and at completely random times the screen goes completely black and the sound is gone for 2-3 seconds and pops right back again. It will do it sometimes none or 2-3 times in a 4 hour period of watching tv. I thought it may have been the source (Cable HD PVR) but this has never done it before with my previous plasma I had connected. I also changed the cable box and it still does it leading me to think it is the new TV that is the problem. Any ideas?