Double-clicking on a publisher file produces: *.pub is not a valid win32 application"

I have a friend with Vista and Office 2007. He's trying to double-click on a publisher file and when he does, he gets the error above.

If you open Publisher up, and do a File>Open, the error does not occur and the file opens up.

What's going on?

 

I am guessing that it is trying to open up the Publisher file in MS Word or another application. I would try right-clicking on a publisher file and select "open with">>"Choose Program" select MS Publisher and check off the check box that says "Always use the selected program to open this kind of file."