Once I had a job programming at a company involved in insurance. We were developing a brand new custom system. Near the end of the project, all of us received an email that told us that the source code was being moved to some fancy librarian program to keep it straight. We were ordered to remove all our code from the PC server as well as our own PCs after the move to the librarian program was complete. Naturally, after years of seeing big failures due to clever moves, I retained a COMPLETE copy of all source code, not only mine, but EVERYBODY ELSE's as well on my own PC intentionally violating instructions.

The move to the librarian program was done on a week-end. When I came in to the office on Monday, I was told that:
1. The move to the librarian program had failed, wiping out all source code on the PC server, even though it had been reported as successful to the other employees Monday morning, causing them to erase all of their copies;
and
2. Attempts to recover the code from the backup magtape failed because the drive used to write backups was broken, but did not report any errors.

One of the top managers came around looking forlorn, and asked me, "Do you have ANY of the source code?" I answered, "I have ALL of it as of 5pm last Friday." He requested that I copy it back on to the PC server, which took all of 5 minutes, so the project got back in business. Had I done what I had been told to do, a multi-million dollar project would have disappeared completely.

Of course, they fixed the backup tape drive and arranged to have each backup tape read by a DIFFERENT drive after each backup operation.