I have a Mac mini 10.6.4 that is set to startup automatically in the morning and to start playing a video in full screen. Then in the evening it is suppose to shutoff. Recently it has started going to sleep instead of shutting down, then when it starts up in the morning the video is not full screen. I have found it in the morning that when it starts up the countdown timer from the night before is still counting down.
System time is correct, Screen saver is set to never, Computer sleep and Display sleep settings are set to never, and shutdown option under Energy Saver -> Schedule is set to Shutdown.