When you attempt to run Disk Defragmenter using the property sheet of a hard disk drive, the following error may occur. We saw how to fix the Disk Defragmenter error using the registry editor in Windows Vista. Here are the instructions for Windows XP systems.
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:
Exit the Registry Editor.
Registry Fix
To automate the above, download dfrgfix_xp.zip, unzip and run the file dfrgfix_xp.reg.
Method 2: Reinstalling the Disk Defragmenter
1. Click Start, Run and type %windir%\INF
2. 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 .INF suffix 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.
Related Posts
- How to Modify or Disable Disk Defragmenter Schedule in Windows 7 and Windows Vista
- Fix for Disk Defragmenter GUI Not Opening in Windows Vista
- Analyze and Defragment Buttons in Disk Defragmenter Do Not Work
- How to Run Disk Defragmenter on a Remote Computer
- Speccy System Information Tool at a Glance
If you enjoyed this post, make sure you subscribe to our RSS feed! We feature Tips, Troubleshooting information, Scripts and Utilities for Microsoft Windows Operating Systems!
Prefer an E-mail subscription?




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?