Final Arena's Graphics Become Distorted

I dont know if this happened with anybody, but when I play ZM Final Arena, after the Round 5 of the JTF, the graphics of the game becomes distorted. The game screen starts to have flashes and the boss becomes blurry. This only happens when I join in the middle of a game. Any solutions how to stop this? Leaving this part, the overall game runs fine for me and I have no problem playing any other mode and map. The specs are Intel Core i7, Intel HD Graphics 4600 and NVIDIA GeForce GTX 860M if that helps.