Another common cause of reboots during shutdown are minor hardware incompatibilities. Microsoft maintains a hardware compatibility list for Windows XP. Only hardware appearing on the list is guaranteed to be 100% compatible with Windows XP. Even so, most people don’t pay any attention to the hardware compatibility list. Most of the time, minor hardware issues go unnoticed, but they can manifest themselves in the form of reboots during shutdown.Unfortunately, I can’t possibly tell you every piece of hardware out there that’s known to cauyse reboot problems. What I can tell you though is that pariphrial devices are especially notorious for causing the problems. This is especially true of high end keyboards and mice with lots of extra features, and of various USB devices. I have even heard of cases in which USB devices would cause the reboot problem if they were plugged directly into the system’s USB port, but the problem would go away if the devices were plugged into a USB hub instead.
Unfortunately there is no quick fix to minor hardware compatibility issues. If you think that your system’s hardware may be to blame then you will have to use trial and error to locate the offending device (or devices).
I recommend starting by unplugging any external devices. If you have a high end keyboard or mouse, then temporarily replace your keyboard and mouse with a generic set. Now boot the computer up and try to shut it down. If the system shuts down properly, then one of the devices that you disconnected was causing the problem. If the system does not shut down properly, then I recommend leaving those devices disconnected during the rest of the testing for the purpose of simplifying the system’s configuration.
The next thing that I recommend doing is to open the device manager and make note of the make and model of your system’s major hardware components. Specifically, you should pay attention to things like network cards, video cards, sound cards, and modems. After you have documented the make and model of each device, then turn off and unplug your computer. At this point, you should remove the computer’s case and verify that the hardware listed in the device manager is what’s actually in your system. Windows XP is notorious for misidentifying hardware devices. For example, I recently helped a friend install Windows onto a new computer. Windows identified his system as having a D-Link network card. When I couldn’t get the card to function, I removed the case and realized that his system actually had a Net Gear card instead.
After you have verified that the hardware listed in the device manager is what’s actually in your system, then I recommend putting your computer back together and going online. I recommend visiting each hardware manufacturer’s Web site and downloading the latest driver for the corresponding hardware device. Hardware manufacturers frequently revise drivers when bugs are discovered. While you are at it, try visiting the Web site for your system’s motherboard manufacturer. It could be that an updated BIOS is available.