Sony KV-32S25 loss of picture and sound

Question

When I turn my set on it works just fine for about 5 minutes. Then I loose my picture (screen goes black) and the sound goes also. If I leave it on a get an occasional flash of light at the top of the screen and occasional sound comming throuht. If I sut it off and come back in a hour or so it come right back on for a few minutes.Thanks for the helprunner