20 hours? hah, you got it good buddy. I go at least once every 3 hours. Used to happen literally once or twice an hour. It was horrible and I almost quit because of it.
It's gotten better since I switched to full screen windowed and turned down some settings. But the most annoying thing is how people say this is Arma's fault. Maybe I'm an idiot or just really lucky, but in every other game mode that I've played INCLUDING other altis life servers I have NEVER experienced black screens or texture bugs this frequently. In fact, I've never had problems with texture bugs, frozen screens, or black screens when I've played KOTH, Wasteland, Exile, Epoch, etc..
In other life servers texture bugs have happened, but absolutely nowhere near as frequently as in Olympus.