The exact same thing has just happened to my PS3 and Panasonic TX 32LZ80L. I brought it up to a different TV to play the console upstairs and when i tried to reconnect to the Panasonic downstairs it wont connect anymore - PS3 still works perfectly on other TV.
My Panasonic has 3 HDMI ports and none will recognise the PS3. Strange thing now is even though it wont display the PS3 if i have another HDMI device on (UPC digital TV) the second i connect the PS3 to another HDMI port it blocks the signal of the first HDMI device (EVEN when PS3 is off!!).
I cant make any sense of it - please help!!
(Also cant find old PS3 scart cable so no joy there and hold down power on boot up to reset video does nothing on Panasonic TV - works on other TV)