How To Schedule Disk Defragmenter To Run Automatically in Windows XP

Go to Start > Settings > Control Panel > Scheduled Tasks > Add Scheduled Task > the Scheduled Task Wizard will appear, click Next.

In the next screen, click the Browse button

Go your C drive > WINDOWS folder > system32 folder > find the file named defrag.exe (NOT dfrg.msc) and double click it

Pick a schedule. If you spend a lot of time with your computer and install/uninstall programs choose weekly, otherwise monthly should be fine. Click Next.

Choose a time. Make sure the time doesn't conflict with any other tasks. Click Next.

Verify your settings are correct.

Check the box next to Open advanced properties for this task when I click Finish.

Click Finish

In the Run: box, at the end of the line that says C:\WINDOWS\system32\defrag.exe, type c: ensuring there is a space between .exe and c:

Go to Start > Settings > Control Panel > Scheduled Tasks and make sure your task is there. Double click on it to make any changes.

That's it!