Picture stretching out and bowing then the tv turns on and off

We have an RCA 52" Widescreen HDTV with a built in DVD player and heve had it for about 3 years. Recently, the TV has been acting strange. It will be working fine then the picture will bow out in the middle and stretch in the corners and then it will get fuzzy at the edges of the screen. Then distortion lines will start to scramble the picture and then the tv will turn off. Then it will come back on by itself but then turn back off and it will repeat this process of on and off a few times, then i wont come on(the picture never resumes while it is rebooting and turning off). We will unplug it for a little while then it will work properly later on but then it will act up again. What do you think the problem is?

Zac Brown