Suddenly: No more image but sound is ok ???

Hello,

I installed my receiver about three months ago, and everything was working perfectly.
However, suddenly, one morning, I wanted to watch TV, but I was getting no more image (just a black screen) but the sound was ok.

My setup is: PS3 and Cable box both connected to the receiver (DENON 1612), and the receiver connected to a Panasonic 1080p plasma screen.
As I said, I get no more image from the cable box through the receiver but the sound is still ok. However with the PS3 (again through the receiver) its perfect.
And, however again, if I connect the cable box directly in the TV its working fine!!

So: receiver works with PS3 but not anymore with cable box, but cable box still works if connected directly in the TV.

I already tried different cables and all HDMI ports of the receiver and its not the source of the problem (since anyway it works fine with PS3).

Any idea??

Thanks very much,

Simon

Thanks for your answer.
I finally been able to resolve my problem by:
1-Turning everything off
2-Unplugging cable box to reset it and replugged after 10 seconds.
3-Waited 3-4 minutes.
4-Turned TV on, then AVR on, then cable box on.
And its now working perfectly!