Textures disappear for a moment and then turn pink and black

Sometimes when i play the screen lag, the textures disappear for a moment(like when they don't load) and then everything turns pink and black for a few seconds, at first i thought it was because of my external textures packs, but after i ask in a group few members told me that they had the same problem even if they don't use any external texture pack, so I concluded  that it's a bug from the game, so I decided to report it