Suddenly when I try to open some of my older Word documents, it says: "You are trying to open a file that was created in an earlier version of Microsoft Office. This file type is blocked from opening in this version by your registry policy settings." Charming! Mark Ottaway
From what you've told me, I think this is probably the result of a security update, KB934181, which is intended to block infected Word files. It's certainly a known problem, and it is dealt with on the Microsoft Knowledge Base at http://support.microsoft.com/kb/922849/. There's also a link page (KB922850) for people who get the same error message about Excel or PowerPoint files.