Most of your consumer gear is a 5 year design. From a simple cable to capacitors and more all this stuff is under heavy pressure to hit the price vs. any long life span.
While it sounds like a heat or other "bad cap" issue, repairs often exceed replacement costs. But do ask for an estimate if they don't charge for that.
My second television is a Sony KDF 46E2000. I bought it in late 2006. Just this week it started doing something weird. Every few minutes, the screen d goes black and there is no sound. The power indicator starts flashing and it basically goes through the same process it does when you turn the television on. After about 30 to 40 seconds the picture and sound are restored. Then a few minutes later the screen goes black again with no sound. Any ideas. As it is only a 720P I'm wondering if it is worth it to call the Sony service outlet or just buy a new 1080P one? If I buy a new one, it won't be a Sony. Not impressed that I am having issues when the t.v. is only 4 1/2 years old. Any help would be much appreciated.