42 inch Vizio will not stay on

Question

Has been working fine. Suddenly I can not get it to stay on. I push the power button, it clicks on and the green light comes on. After a short wait a blank screen comes up the the TV shuts back off. A couple of times it stayed on long enough to see that it said no signal at the top of the blank screen before it tuned back off. I rebooted the cable box, but no difference.Thanks,[e-mail]