Moving of flying black square on screen prevents seeing straight ahead or far away in the distance.

Ref. latest up date to textures on your original minecraft game. When playing a large black square appears and block all vision straight ahead. You can still look down e.g. if flying but not straight ahead. The black square appears randomly and prevents you from seeing what you are building. It comes on when you are walking or flying or standing still to have a look around. I checked the internet and it seems to be a common problem and I can only conclude that it's a bug.