how do I reset my computer to an earlier configuration? win XP?

Answer 1

restore as long as you don't want to go back too far.

Restoring the Computer to an Earlier Operating State
NOTICE: Before you restore the computer to an earlier operating state, save and close any open files and exit any
open programs. Do not alter, open, or delete any files or programs until the system restoration is complete.
1 Click the Start button, point to All Programs→Accessories→System Tools, and then click System
Restore.
2 Ensure that Restore my computer to an earlier time is selected and click Next.
3 Click a calendar date to which you want to restore your computer.
The Select a Restore Point screen provides a calendar that allows you to see and select restore points.
All calendar dates with available restore points appear in boldface type.
4 Select a restore point and click Next.
If a calendar date has only one restore point, then that restore point is automatically selected. If two or more restore points are available, click the restore point that you prefer.
5 Click Next.
The Restoration Complete screen appears after System Restore finishes collecting data and then the computer restarts.
6 After the computer restarts, click OK.
To change the restore point, you can either repeat the steps using a different restore point, or you can
undo the restoration.

This is also available at Boot Up by tapping F8 repeatedly

Answer 2

Use system restore to get to the day it was good.

Answer 3

you can do system restore