Cant tab game into game or loading screen after starting game

So twice every 3 games I play it starts having the issue, my screen turns black or does a quick flash of loading screen then immediately tabs me to my desktop screen. It does that until I restart my computer not even closing and reopening client and ending task work. As a result I come into the game 4-15 minutes late ( 15 minutes was the first time this happened) and we lose most of these games. I can hear me getting into game and i try alt tabbing in it just tabs me out again.