The most literal Windows 10 bug ever
This story occurs back in June of 2015 when the first release of Windows 10 was wrapping up and was almost ready to ship publicly. I was having some really strange problems on my dev box. Whatever program I was using would randomly close and lose my work. I was beginning to think that there was a major ship-blocking bug in Windows. Things got stranger and stranger as I looked into the logs and telemetry from my machine. Nothing was crashing. Everything seemed to be working normally. It was all very strange.
Something that must be noted is that I was using a terrible hand-me-down third monitor ( this ugly beast ). Those monitors were used during Windows 8 development because they were the only desktop touch screen monitors on the market. They had a lot of flaws. One of the flaws is that the touch input always went to the primary display, even if that wasn't the touch display. This thing was of course not my primary display. It also had enormous bezels all the way around. And it put out a lot of heat.

All of that led to a tiny spider taking up residence in the top right corner, unbeknownst to me. A little spider that would register as touch input when it crawled on the screen. Touch input. Top right corner. That's where the close button lives!
Basically whenever this little spider decided to leave its warm little home in the bezel it would crawl over the screen and would close whatever program was open on my primary screen. Often when I was in the middle of typing something. It took me a good week or two to realize what was happening. The big clue was that some of those "touch visualizations" were appearing on the primary display, so I looked over to my right and saw a little tiny spider. I can't remember what happened to the spider. I don't think I hurt it because it was too funny. I just disconnected the USB cable for the display so that it stopped sending touch input.