Smite gives the screen white stripes

I updated my LoL to 4.20 yesterday and wanted to test the new jungle items in a custom game. Everything went fine, until i used smite. From this moment on, white stripes (2 or 3 per second) went over my screen, from the smite symbol to some jungle camps. Once smite wassnt on cooldown anymore, the stripes stopped to appear. I used smite again, they came back. 2-3 stripes per second is a lot and makes the game unenyojable for me.

I repaired the client and i installed league new, the problem stays.

Since i can only play on the weekends it would be great if someone has an answer