Ubuntu 9.04 Hangs on Shutdown/Restart

After updating my Ubuntu(Jaunty) kernel image to linux-image-2.6.28-13-generic, the shutdown and restart started to hang. I have spent many hours scratching my head to find a solution. In general, such things occur when shutdown process cannot terminate a running process properly. In my case it was caused by wicd network manager. I had to uninstall wicd and install the native gnome-network manager. Now the restart and shutdown works like a charm.

For other causes this article may provide some useful information.