I detailed here the problems I had trying to craft a script-based backup solution using vshadow and robocopy. I never did figure it out, even after a BIOS upgrade and hours and hours on various forums. I ended up downloading a trial of SyncBack SE, which has worked very well so far, even with open files like Outlook PST files. I am not thrilled about having to go with a commercial solution, but I have to say it is pretty cool and convenient.
(Hat tip to Brian Hinkle.)