Login Screen doesn't Work.

Since the new patch I cannot play league. After I try to run the application it takes fairly long for anything to happen. After like 5 min I can finally see the loading screen but it is usually just a dark blue rectangle, sometimes I can see the windows where I need to put my name and other UI but I cannot press anything. It also starts to lag my computer quite substantially (my computer is not that bad it runs league on high with over 60 fps, also other games applications rune as usual so it is not a general problem of my computer.).

I have tried reinstalling League twice but it didn't help so I no longer think it is the fault of the patch.

Thanks for understanding.