|I'll bet when this happens you can go into windows explorer and unmap the drive, then immediately remap it and it works. If you haven't tried that, do so. If that does the trick, write a batchfile to perform the two commands and put it in the \Windows folder|
Then the when users start having probelms, they can just open the run command and type the name of the batchfile and hit Enter and it'll unmap/remap the drive.
Windows is notorious for not holding a drive mapping decently. I've never figured out why (hey, it's windows) but this is how I've always worked around it.
It matters not how straight the gate,
How charged with punishments the scroll,
I am the master of my fate;
I am the captain of my soul.