After Login in The LoL freezes my pc

Well i didnt play lol for a week maybe and when i made the patch 6.5 it would crash the launcher, then i tried to re-install and it worked!! but... yesterday after i log in the lol would freeze my pc and would force me to restart my pc, since there i already re-installed lol for the 2 time... but nothing works, tried to change the compatibility to win 7 and still the same, pls if someone knows the solution to this problem i will be quite happy for ur help.

Ps: my pc is win 8.1