Screenfreeze on login

So, it occurs again... I can do anything on my computer i can run any game, except LoL. What actually happens is: when I log in i get the homescreen where you can play for 2 seconds, than it starts to load the boxes with skin sales and champ sales and idk high elo matches to spectate. Right at that moment my computer just freezes. I can talk freelo trough skype or teamspeak.

I tried:

• Repairing LoL
• Re installing LoL
• System recovery on my computer
• Run LoL in windows 7, as admin.
• And so much more

I have a laptop , Intel I5 core, Gforce GT 750 , 3.1 GHz

This occured just randomly , not directly after a patch.

Can someone help me?