Computer won't turn off
Sometimes a computer will experience a problem and needs to be turned off. But you turn it off and it stays on! The way to turn it off when this happens is to hold in the on/off button for about 5 seconds - until the computer turns off.

Phantom Devices
Phantom devices can appear for any number of reasons. The most common reason is probably a shutdown error with a removable drive.
The official word from Microsoft on the two correct ways of removing an external or hot-swappable disk (or other device), as described in the Windows XP Professional Resource Kit: If the Safely Remove Hardware icon appears in the taskbar notification area, you must use it. If the Safely Remove Hardware icon is not in the notification area, you must use Device Manager to uninstall the disk before you unplug it."
The improper method is the one many of us use: we simply unplug the device. This usually works, as long as the device isn't actively being written to or read from. You unplug the device, hear the audible "device unplugged" confirmation tones (a descending "ding-dong"), and that's that.
But simply unplugging a device runs the risk of losing data through a delayed write, or open file, or similar problem. You also risk of leaving behind a phantom drive or other resource assignment, because the OS doesn't realize the device is gone.