My own fail
Years ago, the company I worked-for had a microcomputer (16-bit, though) running Xenix and a package of Business BASIC applications. The system ran nicely but one day we got a warning that the disk drive was nearly full. Business being good, too much of the drive was active to be backed to tape, and the computer itself could not handle a larger drive. Sooo... we bought a new computer with a larger drive, and I committed myself to transfer the data from the old drive to the new one. The only good way to do it was to write programs to dump the data over an RS-232 connection, accept it, and write it to the new drive. In itself, not too big a deal. We set the transfer date to a holiday, July 4th, when I would come in, finish the programs, and start the transfer.
Came July 4 and I was feeling awful... just terrible. I dragged myself to the office anyway and worked on the "acceptor" code until I simply couldn't do it any longer, but I thought I had finished it and the transfer wouldn't take more than a few hours. I went home, then dragged myself back into the office the next day with a temperature of 104F and tried to start the transfer. The data was making it's way down the RS-232 line but was being scrambled on the disk, so I started going through the "acceptor" code. I found things like:
IT (blijk(i) <+ feemble} TENH GOOT ++++;
Utter gibberish. The second half of the program was ALL gibberish. Apparently I wasn't able to write comprehensible code with a temperature of 104 or higher. I finally gave up trying to fix it, bailed out of the office until my fever went down, then returned to write the code properly and run the transfer--which worked fine afterwards.