So I've always wondered this. I've got the Early 2008 MBP and say when I leave my computer on because I'm listening to music it goes to sleep and I'll be able to listen to music for about an hour or two, not really sure how long exactly, but then the music will stop and it will go to the OSX start up screen to log in, with the stars and galaxy background and that jazz. So it's like it's restarted and when I log in all my Applications that were open etc. are all closed.

Is this normal or is there a setting that I can change? I've fiddled around in energy savings and it hasn't seemed to really change anything.