How do I get FF to always open doc files with Word 2007?

In Firefox 3.0.4, when I'm on a board, and one of the entries includes Word document, when I click it, Firefox always asks "Open with what..." and grays out the "always use this..." option.

When I click the file it isn't asking about a Word document, but that is what the attached file is...

I was going to attach the file, but see nowhere to attach it. the file type it is asking about is

application/octet-stream

and it isn't showing the extension, which is doc.

??

Regards,
Chuck Billow