If you have followed the instructions in this article and still experience problems with your Ubuntu Linux distro hanging on shutdown, you can enable verbose booting and shutdown in your kernel options. I find this to be a very useful option to enable, and tend to leave it enabled at all times so I notice any potential problems with Ubuntu booting and shutting down. To enable verbose booting and shutdown in Ubuntu:
Before you begin, open a terminal window and type this command to back up the file:
sudo cp /boot/grub/menu.lst /boot/grub/menu.lst.old
Type this command to edit the menu.lst file:
sudo nano /boot/grub/menu.lst
Near the end of this file you will find your kernel listing similar to the above graphic. You will want to remove the "quiet" option from the kernel line of your default kernel. Update Grub:
sudo update-grub
The result of this modification will be a verbose boot and shutdown screen. You will want to look for problems during your Ubuntu boot and shutdown for problems. Modules and services that are loaded will be followed by <OK>, if any modules or services are having a problem the line will report a <FAIL> showing you what area of your system to investigate next.
If none of these troubleshooting tips resolved the problem with Ubuntu hanging on shutdown you still have a couple good places to turn to help you resolve your problem. The first thing I would recommend following these tips would be to visit the Ubuntu Forums and post your problem there. Be sure to include the contents of /var/log/messages and /var/log/dmesg as well as any errors you have seen since turning on verbose booting and shutdown. This will give members the initial information they will need to help you resolve your problem and avoid delays.
Lastly, if you have had no luck with any of these troubleshooting tips there may be a bug in the version of Ubuntu you are running. Your final step should be to visit the Ubuntu bug-tracking system on launchpad and search for similar problems, and failing to find a bug report, file a report yourself. Rarely will it come to this. Good luck and keep it Open Source!