Not quite as disastrous but when I was at university the resident administrators configured the entire site's tftp server (everything was netbooted Suns) to boo

Not quite as disastrous but when I was at university the resident administrators configured the entire site's tftp server (everything was netbooted Suns) to boot from the network. This was fine until there was a site-wide power blip and it was shut down. When it came back it couldn't tftp to itself to boot because it wasn't booted yet (feel the paradox!). Cue 300 angry workstation users descend on the computer centre with pitchforks and torches because their workstations couldn't boot either... Bad stuff doesn't just happen to Windows networks.