TV SCREEN GOES BLANK. My TV will play fine for 10-20 min. after that the screen will go blank.

Question

My TV will play fine for 10-20 min. after that the screen will go blank. Sometimes the screen will light up but no picture. I have no problems with the sound. When I unplug the power cord for a few min. and plug it back in the TV works for a few min. and does the same thing over again. The TV is only about five months old. None of the vents are blocked and nothing has gotten inside of it, and I have always kept it pluged into a surge protector. I have been the only owner of this TV. Please help if you can, and thanks for any advice... [e-mail]