Sometimes, when I try to turn off my computer, it doesn't shut down. It would either quit all programs (including finder) and just show the wallpaper, or it would go to the blue-ish screen (a normal phase in the shutdown process) and the wheel on the bottom would spin forever. In either case, the computer just freezes at that point and I have to power cycle it manually.
I noticed that this occurs more frequently if I don't restart it for a couple of days (3-4 days max), but my friends are able to go on without a restart for 2-3 weeks at a time. I tried reinstalling OS X to no avail. I now also quit all my programs manually before I try to shutdown (don't know if they affect anything) but that does not appear to help.
EDIT: I'm using a late 2008 MBP with OS X 10.6.5 (10H574)
I noticed that this occurs more frequently if I don't restart it for a couple of days (3-4 days max), but my friends are able to go on without a restart for 2-3 weeks at a time. I tried reinstalling OS X to no avail. I now also quit all my programs manually before I try to shutdown (don't know if they affect anything) but that does not appear to help.
EDIT: I'm using a late 2008 MBP with OS X 10.6.5 (10H574)