First of all, if it has a sleep timer, I would recommend setting it so it goes off before you fall asleep.
Seriously, I looked through the user reviews at CNET. Although 15 of 16 reviews were very positive, one person cited "a high pitched squeal" which Toshiba has not resolved. The rater said this happens when the TV is getting a signal from 2 different inputs. I don't know if the rater or Toshiba have that opinion. Have no real idea what that means unless there's an internal problem if a signal from one input leaks into another once in a while. What is connected to the TV?
Since months can go by before it happens again, it may not be worth the cost of a bench check, especially if the problem can't be replicated.
In late 2009, I bought a new Toshiba LCD TV, model 40RV525U, and it worked fine for about a year. Recently, it's begun behaving erratically. At seemingly random times, the picture will freeze and the set will emit a high-pitched shriek that always startles me, and it often occurs while I'm asleep, adding extra stress.
The set becomes unresponsive, and I can only shut it off by unplugging it. After I plug it back it, the set works fine, until it happens again, several weeks (or months) later.
I have no idea what's causing this, and the set is no longer under warranty, so I was wondering if anybody here had any familiarity with the issue, and whether it would be more cost-effective to simply go shopping for a new television.