This is just a guess but some TVs have a "sleep" function where if it's set to do it it will work for another hour, or whatever the setting is... then automatically turn off. It's meant I guess for people who like to fall asleep to the TV being on but don't want to leave it on all night. I would check your menu settings and see if this is the case for you.
Laura
November 2009
Automatic Answer
We may have found other answers which could help you.
howtomendit.com for free repair help, information and advice.
Try fixfault.com to fix televisions.