Zenith c32v23 picture on television will go out after about 30 minutes but sound perfect

I have the same problem with my C32V23. The picture and sound are perfect for about 20 to 30 minutes, and then "blink" - the picture's out but the sound is still perfect. I tried changing the power supply strip, changed the supply supply location to another receptacle, I upgraded the factory-issued cables on the DVR/receiver box to "Monster" brand cables, ran the cable from the wall direct to the TV, switched cable boxes out to a non-HDTV system,all to no avail. Bought the TV new from the now-defunct Conn's back in '02. The problem ironically started after my wife and I switched the cable receiver box to an HD-ready unit. Our cable company (Time Warner) did not have a DVR box with HD capability until recently and we've used the TV all this time without enjoying the high definition features. Now we're trying to decide to get it repaired or purchase a new one. Our wide-screen Mitsubishi brand has never given us a problem in the 10 years we've owned it. I have the same problem with my C32V23. The picture and sound are perfect for about 20 to 30 minutes, and then "blink" - the picture's out but the sound is still perfect. I tried changing the power supply strip, changed the supply supply location to another receptacle, I upgraded the factory-issued cables on the DVR/receiver box to "Monster" brand cables, ran the cable from the wall direct to the TV, switched cable boxes out to a non-HDTV system,all to no avail. Bought the TV new from the now-defunct Conn's back in '02. The problem ironically started after my wife and I switched the cable receiver box to an HD-ready unit. Our cable company (Time Warner) did not have a DVR box with HD capability until recently and we've used the TV all this time without enjoying the high definition features. Now we're trying to decide to get it repaired or purchase a new one. Our wide-screen Mitsubishi brand has never given us a problem in the 10 years we've owned it.