League Of Legends Wont Work Please Help!!

So here is the deal,

Every time when I try playing Summoners Rift 5v5 My Screen would immediately turn black and I would be able to do nothing. Forcing me to close the league client, however when I press the "Re-Login" or "Reload: Button the same thing happens...

So when I officially close the League Patch client I Sign in and press the Button "Legacy Client" When I press it, it starts to work but when i wait about 2m my whole computer shuts off disabling the process of going into the "legacy Client"

I don't know what to do in-order to fix this situation and I would like help in-order to fix this. Thanks for reading this and have a nice day!