Leif writes, I have cable internet at home (cox) and Earthlink high speed at work. After being on line and shutting down, I get the message “Others are logged onto your computer, Shutting down now will…”. What is going on and how can I prevent my computer from being used as a relay station for some hacker?
Windows XP includes a number of cryptic error messages and nothing is more unnerving than the possibility that someone or something might be logged into your computer. A little more explanation in the message would go a long way to clearing up the confusion. The good news is this message has nothing to do with a hacker using your computer. There are two common explanations for what might be happening.
The most common cause of this message is when you have more than one user profile on your system. For instance, if you and your wife each have your own profile, they can both be logged in simultaneously. When you go to shut down your wife is still technically logged in and so you get an error message warning that someone is still logged in, even if you were the only one using the computer for the last several hours.

In this scenario, you are seeing the error message do to the Switch User feature in Windows XP.

A second possibility exists if you share resources on a network. If someone is logged into a resource on your computer from another computer on the network, including printers and files (depending on the network configuration), you will get this warning during shutdown. To find out which user is specifically logged in, you can launch the Windows XP Computer Management utility by typing compmgmt.msc from Start > Run. Any connected users will be lisetd in the Shared Folders > Sessions section of Computer Management.