One of my clients had that "phantom drive mapping" problem not long ago. I think they traced that problem to Microsoft Office's FindFast that gets installed in the startup group when you install Office.

Personal opinion here, but FindFast is the first thing I throw in the trash after installing Office. I haven't found any use to it other than eating CPU time. :)

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>In explorer, I noticed my "D" drive would apparantly randomly get mapped to a drive on the server that was already mapped to "S". I disconnected it because there was no need for it to be there. Then one day, I noticed the connection between me deleting the connection and the ISO. I looked at the shortcut the the app, and it had changed itself from the "S" drive to that mysterious "D" drive!