Q. I have a teenager who wants to be on the computer all night. Can I lock her out at a given hour or schedule the computer to run a certain number of hours a day? Any help would be greatly appreciated. We have Windows XP.

A. Windows XP includes a basic but effective tool to limit computer use. This tool, which makes a good parental control feature, is accessed via the command line.

I'm assuming that your daughter is using her own Windows limited account. Otherwise, you would have to limit the whole family's computer usage. You can learn how to set up a limited account through a column on my Web site.

To open the Windows command line, click Start>>All Programs>>Accessories>>Command Prompt. At the prompt, you'll use the following command:

net user Name /times:

To make this command work, replace "Name" with your child's Windows account name. Then include which days and hours the computer can be used. This may not be intuitive, so be deliberate. List OK times rather than forbidden times. Here's an example:

net user Ian /times:M-Su,6AM-9PM

In the example, my son Ian is allowed to use the computer Monday through Sunday (every day) from 6 a.m. to 9 p.m. Any other hours, such as the middle of the night, are off limits. (Note that there is a space after Ian's name.)