leaving the computer on, i came back and realised that my computer had shut itself down. so i restarted it, and went through and "checked and fixed" errors that were on my pc (stuff didn't unmount) (i think).. anyway, i thought this was weird but again left my computer, came back about 20minutes later to see the screen saver on, i decided it was all going to be ok this time, but i came back around 5-10minutes later and it had turned of... it doesn't "shut down" because it doesn't unmount. it just turns my pc off... any way this could be fixed? anything anyone could suggest? this is my second day of linux, so i'm pretty stuck, i've gone through most of the confs in gnome and can't find any settings "turn my computer off if it doesn't look like i'm comming back in the next 30minutes"
any help would be appreciated!