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 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.
HKEY_LOCAL_MACHINE \ SOFTWARE \ Microsoft \ Windows \ CurrentVersion \ explorer \ MyComputer \ DefragPath
C:\Windows\System32\dfrgui.exe
To automate the above, you may use the REG file (dfrgfix_vista.reg) attachment below.