TV acts like a timer is controling the power...comes on only at night

I work shift work. One morning when I got home my two girls had a slummber party and all the girls had been watching movies all night on our GE Big screen tv Model # 46GW945. The next couple of days I would try to watch tv and the tv controls would not allow me to turn the tv on until 8 PM that night...once the TV was on I started looking for a timer of some sort to see if the girls had messed with this...no luck but I did turn the lock for the front panel to OFF....then the next day it happened again.....now it is everyday and I don't know what to do....it's been going on now for a week....I can't find a reset button to try to reset the tv so what do I do now...I have read in several forums that if you unplug the TV for thirty minutes this might do the trick....I don't know what to do and there is no TV repair shops in my area...the closest one is about 100 miles away...kinda hard to load this tv in the back of the truck and take it to them...any suggestions to try...I'm at my last straw!