OK, so you cannot shut down to reboot. Before just turnning off the power to your system be sure to try the
task manager.
Hitting the Ctrl Alt and Delete keys at the same time will usually bring up the task manager and show you
what tasks are running.
If one of your tasks is not responding, highlight it and click on end task. You may have to wait a coulpe
of minutes but this may free up the system and allow you to shut down properly.