Note when your box goes off, and check both your TV and cable box for any timer settings. If you don't have any timers set, then call your cable provider.
Boot up a Ubuntu live CD install and go into try without installing, then when it has started up, go to parted, find the partition with Ubuntu on it and...
This could be any number if things. Combustion is starting the truck, but then it's being inhibited by something, fuel line or battery issues, perhaps. Take it to a diesel...