Error “The Disk Defragmenter is not installed on your computer” in Windows XP

When you attempt to run Disk Defragmenter using the property sheet of a hard disk drive, the following error may occur. We previously saw how to fix the Disk Defragmenter error using the registry editor in Windows Vista. Here are the instructions for Windows XP.

The Disk Defragmenter is not installed on your computer. To install it, double-click the Add or Remove Programs icon in Control Panel, click the Install/Uninstall tab, and then follow the instructions on your screen.

Use one of these methods to solve the problem.

Method 1: Fixing the Defrag Path in the Registry

Click Start, type regedit.exe, and press Enter

Navigate to the following location:


Double-click (default) and set its value data to:

C:\Windows\system32\dfrg.msc %c:

Exit the Registry Editor.

Method 2: Reinstalling the Disk Defragmenter

  • Click Start, Run, and type %windir%\INF
  • Locate the file dfrg.inf, right-click and choose Install

Note: There will be two files, namely dfrg.inf and dfrg.pnf. You’ll need to right-click on the INF file (identified by a text pad and gear icon in it) and choose Install. Note that the file extension is not shown in Windows Explorer unless the Hide extensions for known file types setting is disabled in Control Panel → Folder Options → View tab.

This reinstalls the Disk Defragmenter.

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Ramesh Srinivasan is passionate about Microsoft technologies and he has been a consecutive ten-time recipient of the Microsoft Most Valuable Professional award in the Windows Shell/Desktop Experience category, from 2003 to 2012. He loves to troubleshoot and write about Windows. Ramesh founded in 2005.

1 thought on “Error “The Disk Defragmenter is not installed on your computer” in Windows XP”

  1. I have tried everything to get my disk defrag to work. I had defender pro installed on my computer and it messed everything up. It had a defrag program with it and when I deleted the program my defrag would not work. In my inf file I have a bunch of files that say AER_1026.ADM, and they look the same just different numbers, there are 38 of them. They all say unknown application. I’m not sure if I can delete them. I have tried to do a search on them and I get different answers. I am also missing my task scheduler. I don’t know what to do. I have been working on this for about a week. Can someone please help?


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