PBE gameplay issue

My friend and I have been playing pbe to try the new poolparty skins, akali rework, and one for all etc. and the game keeps freezing at random points, sometimes where it crashes the whole game and forces me to restart my whole computer because it wouldnt load back. The screen would freeze then turn black (the computer restart happened twice). I really hope this issue gets fixed, because this has never happened before, and my friends computer, also freezes but their screen doesnt turn black