One of my favorite bug fixes took me two weeks to find, and the fix was to swap two assembly language instructions (this was a bug in the Apple Newton context switch code, and swapping the instructions let timer interrupts happen reliably, which is kind of important for thread scheduling). We'd been having intermittent problems for months, with no smoking gun. I got mad at it, and found it.

No one was upset at the fix -- if anything, the checkin's brevity communicated its correctness -- and I got a couple of pats on the back for it.