The computer worked fine yesterday.

Now you can't check email. Programs won't run. The printer won't print.

Could it be that new program you installed this morning?

That extra speed your friend promised before changing the system settings?

The kids?

If only you could turn back the clock, and restore the computer to its healthy condition that existed yesterday or last week.

That's not a wild dream for computers using Windows Me or Windows XP.

Both master control programs have a little-known feature that can be a life-saver when problems strike.

Called "System Restore," it returns the system to a previously known "good" condition when everything did work -- without loosing new emails or documents.

Windows Me and XP automatically take a snapshot of your computer's configuration, and store it on the hard disk. They create one at least every 24 hours.

A series of known, good-configurations are probably stored on your computer right now. If a problem occurs, you can roll back to conditions that existed in the good old days, when the computer did work.

To check out System Restore, click on the Windows Start button, point to All Programs, System Tools, and select System Restore.

The calendar displays existing restore points.

If you don't use the computer often, consider creating new restore points every few days. You also can create and name restore points before events that might cause problems.

Among them: Changing the system settings, installing new programs, or letting other people use the computer.

To make a restore point, click "Create a restore point" in the System Restore dialog box. Click Next; type a description, such as "Before changes," and click Create.

There are several ways to use System Restore.

If Windows does not start normally:

Turn the system off. Press the power button again, and press the F8 key when Windows tries to start. The Windows Advanced Options menu should appear.

Use the arrow keys to select "Last Known Good Configuration." Press Enter.

If a menu appears, use the arrow keys to select Microsoft Windows XP or Me. Press Enter.

If Windows does start:

Go to System Restore. On the "Welcome to System Restore" page, click "Restore my computer to an earlier time," and then click Next. Select a restore point, and then click Next. If a message appears, click OK.

On the "Confirm Restore Point Selection" page, click Next.

Windows should restore the previous configuration, and restart the computer.

Go back until further in time until you find a restore point that works.

Remember that System Restore works only for a core set of files needed to operate the computer and run programs.

It does not bring back old copies of personal files, email addresses, or items deleted from the Recycle Bin.

If you accidentally delete one today, System Restore will not bring back the copy that existed last week.

You'll get only the files that existed when you performed the restore.

Scripps Howard News Service