I have noticed this in every linux OS I have tried. When I attempt to a reboot, it hangs and forces me to manually shut it off. I cant imagine that this is good for my netbook and was wondering if this can be changed. I have tried Mint 12 & 9, Ubuntu 11, and Xubuntu and they all do this.
In order to find out why it is hanging you could remove the "quiet splash" flags from grub2. This should allow you to see where it jams.
then change the line
Then save, and
Now when you boot/shutdown the splash screen will be gone and you'll get lots of info as to whats going on.