This has happened a few times on our staff laptops. A user has recieved a .doc attachment in Outlook 2007 but when they double click on the attchment it opens word but not the attachment (such as the image below). This can also affect word documents in the computer, i.e. desktop, and in work areas. Also, when you try to quit Word it crashes with "Word is not responding". Before we've got around this by deleting the (local) profiles which seems a bit drastic and a web search shows a lot of identical/similar problems but no concrete answer.
Windows 7, 32-bit, No SP1 installed (yet) Office Enterprise 2007.