... SteveJS asks.
I saw many curious bugs in my developer life, but here is one that I remember: Back in Windows 2000 shipping days, one of the coolest features there was PnP and power management. This also caused us to ship later than expected because the whole driver model changed in order to deal with things like power management. And many (third party) drivers had lots of troubles here.
One particular driver was responsible to power-on a certain type of motherboards, and had a bug in the way the voltages were restored by the controlling chipsets. Due to this, whenever you attempted to return from standby, the voltages ended up were incorrectly, and the motherboard started to emit smoke. Of course, to repro the bug you needed a fresh motherboard every time!
P.S. In case you are wondering why I'm still awake at this hour: because some doll in our garage started to say continuously "I'm feeling great!" at around 3.00 AM. The speaker was quite noisy, and annoingly noticeable in the silence of the night. Well, I tryed to ignore the sound for 30 minutes, but I couldn't stand it. So I went in the garage and I silenced the dool. I had to take its batteries out, since there was no OFF switch! Another usability bug.