Filetype deactivated on Explorer

When I try to open an application ex. *.doc with doubleclick on the file, I can't open the document because the .doc extension is not linked with word.

Now I wanted to change the link in Explorer in the menu extras, folderoptions, filetypes. I logged in as "Administrator" but the menu appears as deactivates and is grey represented.
Where can I activate the menu so that i can configure the links for the extensions?

Thanks in advantage for your tips

With regards

Ramon