It is almost certainly what BigT said… even from your thread title, it was possible to guess the problem (it’s very common). Turn off hardware acceleration and I’ll bet you it goes away. Hardware-accelerated texture corruption is an everyday part of life when you use graphics cards, except in games the textures can get redrawn 60 times a second and constantly loaded/unloaded anyway so you might not notice it. In browsers you’ll see that happen. Happens with Chrome and Firefox’s hardware accelerations from time to time, across different video cards, even if they’re totally fine in games.
Just try it.