Try calling your cable company and ask them to refresh/reset the box, or see if there are any updates available for it. In many cases, what you're experiencing (no or blanks signal with audio) is a result of a DHCP copy protection limitation. The resets can often times fix these issues.
Keep me posted.
i just installed a samsung ln40b650 it worked fine with a caqblevision cable dvr box the set worked fine.
then we turned it off for about an hour then turned it back on.
we have only a white blank screen no picture but we have sound.
this condition is lon the tv cable hdmi and the compoent dvd input after changing the source same problem .