If your optionalfeatures.exe or "Windows Features" dialog box is blank or empty.
If you try to access the 'Turn Windows Features On or Off', through, the Control Panel or by simply typing optionalfeatures.exe in your start menu's search box, the following dialogue box is expected to open.
But if the 'Turn Windows Features On or Off' / optionalfeatures.exe gives you a blank or an empty box, it is quite possible that the component store that contains information about Vista components has been corrupted.
To rectify this problem, type the following command in cmd and hit enter:
reg delete HKLM\COMPONENTS /v StoreDirty
But this is not known to work for all ! In that case a Vista Repair would be an option to consider. Additionally you may check up KB931712.
