Such simple things can screw up authentication systems. Sigh.
I had a problem once with an admin who maintained my systems quotations. Before Borland came out with a decent spreadsheet, I was forced to use Lotus 1-2-3 for DOS. It required a key diskette in the 5 1/4" diskette Drive A: to operate. Pain in the butt, but managable. Until my admin's install started denying her key diskette.
After much time and mental anguish, I was able to determine the reason for the failure. She got tired of storing and retrieving the key diskette, so she cleverly attached it to the file cabinet right next to her PC.
With a refrigerator magnet.
Face palm!