For those not paying much attention to Samsung's 650 series
of LCD HDTVs, this very well may be the first you've heard of any "auto shut off" issue. For owners, we can almost guarantee it's not. As of last month, Samsung has issued a firmware update meant to cure the nagging issue on some sets which turned themselves off sporadically. The LN40A650A1F, LN46A650A1F and LN52A650A1F
are called out specifically, and Sammy recommends that you only install the update if your set is one that has a mind of its own. Give a shout in comments to let us know if this does indeed solve the problem.
[Via TV Lamps 'N Bulbs