Error “The Disk Defragmenter is not installed on your computer” when launching Disk Defragmenter in Windows Vista

When you open the Properties dialog box for a local hard disk and click the Tools tab, one of the following symptoms may be seen:

• The Defragment Now button is unavailable
• When you click Defragment Now, you receive the following error message:

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.

• Click Start, type regedit.exe and press ENTER
• Navigate to the following location:

HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ explorer \ MyComputer \ DefragPath

• In the right-pane, double-click (default) and set its data as follows:

C:\Windows\System32\dfrgui.exe

• Close Regedit.exe

OR

you may use the REG file (dfrgfix_vista.reg)