Black Screen and Alt Tabbing

Hello, i've been experiencing this black screen after going back to the menu post match at he part when it shows your exp earned. Another issue is there is some times when Alt+Tabbing to open or view some apps, it doesn't let me open the game. I can hover the mouse icon at the game at the taskbars but i cannot open it.

My solution to black screen in alt tabbing is just exiting the game via Alt+F4 and for alt tabbing issue, just ending task via task manager.

I also auto optimized the game via Geforce Experience because i feel the game is stiff and slow.