A bit earlier today, I somehow managed to make Internet Explorer show polygon edges with black lines on HTML elements. Guess the HWA had an hiccup there.

(Yes, IE9 does use orthogonal triangles for rendering.)

All the time when I had my old graphics card.

I once tried to install Lego Digital Designer on a low-end, 7-year-old computer, and it basically broke everything. The GUI flickered, and everything froze up. IIRC, the problem was outdated graphics drivers.

Also, this isn't my story, but my sister recently tried to install Petz 5 on Windows 7. About half of the sprites would display as black squares. Her workaround was to switch the resolution to 1024x768.

Occasionally, whenever I'm in the middle of watching a YouTube video, or after it's over, my whole screen will flash in odd colors for a little less than a second.

Wasn't on my computer, but for some reason, videos on YouTube on Android would sometimes flicker mysteriously (Like the picture repeatedly goes black very fast, like at least 15-20 times/second)

On my old (6 year old) computer I had many problems. One common one was in almost any time I move a window a trail of that window. So that was annoying.

My computer would sometimes freeze up for a second and it's display would look like some freaky demon is trying to show me it's face. It's very odd.

It happened once: horizontal black lines flashing, and I could not reproduce it. I can only blame it on external magnetic fields.

"A worm has entered your computer. Initiating back-up service..."

Wtf?

Just this morning my laptop froze on startup. It showed the background, but didn't load the taskbar or the desktop icons. Restarting it fixed it, though.

Mine occasionally will invert the colors and flash a few times before the graphics reset and I get the little pop-up in the bottom-right saying that my video card recovered from an unexpected crash. It only happens when playing H.264 video.