|See that tiny dot in the centre? ITS ALIVE.|
It's not on the surface of the screen, yet it's not software - what we have here is an actual bug that somehow crawled in between the LCD panel and the backlight. A quick googling shows that this seems to be worryingly common.
It's been wandering around in there ever since, unable to find a way out. Whenever it hits the edge of the panel, it'll crawl along a bit and come straight out. My plan is to wait for the bug to escape of its own accord or starve to death (hopefully at the edge of the screen so it's not much of a nuisance).
If you're as intrigued by this as I am, have some low-quality videos of the bug exploring where no bug has gone before.
It's only Tuesday. There's still plenty of time this week for even weirder IT problems to spring forth.