Can't open microsoft documents stored on my passport

All of a sudden I can not open any microsoft documents that are stored on my passport.  It wasn’t a problem until today.  The message says that word cannot open this document.  The document might be in use, the document might not be a valid word doucment or the file might contain invalid characters.  If i move the document to my desktop, it will open…but not from the passport drive.  The external drive is not even half full.

Trems,

If they open when copied into your desktop, then there is a possibility of data corruption to consider. What happens if you copy the files to new folders inside your WD Passport? Do you experience the same result?