For the record, I'm hitting a wall with Windows7 users whose shared VW files are on a MacOS X Lion server.
Some users can open VW files, others who try to open the exact same file get a Vectorworks dialog stating, "This is an unrecognized file. It may be a Vectorworks file created by a newer version of the application. It may be a very old MiniCAD file. It may have been created by another appliaction, or it may have been corrupted by a hardware or system error." If the file is moved to the users' desktop, it opens normally.
Not seeing many threads on this issue, so am really hoping for insights or experience from the broarder VW community. Ack!