So I've had a long-standing issue with this Samsung in that it occasionally turns itself off - or rather, it gets turned off because of stray light in the room or from the screen itself.
It seems that the IR receiver (for the remote control) is simply too sensitive. Perhaps it is defective or out of alignment, but in any case it's just not right. Samsung has not been helpful in resolving this (make sure you aren't pressing any buttons on the remote, make sure your cable box isn't set to turn the display off, etc). The problem occurs on any input and even when all remotes are physically removed from the room. Replaying specific moments on ESPN or CNBC (usually bright transitions or the stock ticker) via DVR can faithfully reproduce the issue about 3 out of 10 times.
Another hint that it's receiving stray commands is that you can see the red LED blink just before switching off - the same thing it does when receiving legit commands from the remote.
Anyway, this happens infrequently enough that I never sent it back but now I'm well past my warranty and for whatever reason it's turned off three times this morning so far (it's a sunny day). My plan is to open up the case, access the IR receiver and put a gel filter (like neutral gray) over it in an attempt to reduce its sensitivity.
What would be great is if there was a service menu option for tweaking this sensitivity, but so far I've not found one!
Let me know if anyone has any experience with this bizzarre sort of problem and can offer any tips... thx!