Has/had (don't know if it's been patched) a nifty bug where a 4-bit group identifies the state the spacecraft is supposed to be in. The problem is when the spacecraft reboots, that value starts off uninitialized, so whatever value just happens to be sitting at that point in memory gets used. Not a huge problem, because when the spacecraft reboots (it happens) we can just telecommand it to the right state. Except for one problem: One of those states is "I'm on the launching pad and shouldn't listen to any radio telecommands, but only commands from the hardwire interface." Which means we can't remotely command it out of that state anymore, and it will at that point be a dead orbiter.
Space software is exciting!