I encountered a real fun bug where a game on linux crashed and a ghost of the game remained on the monitor even after it was connected to a different computer and power cycled, it remained for days. Some really interesting cascading bugs there.
Software isn't supposed to be able to cause that. That's on your monitor.
What I convinced myself of after a few minutes being sure I wasn't hallucinating was that the graphics driver was pushing out malformed data in some way or the other which was triggering bugs in the monitor hardware/firmware, which is easy to believe are plentiful. It would be an interesting project to try to track down and replicate the bug.