crash and windows notification sound at mostly 1:30 or mid game

Hello <3 sooo my game completly freeze along with windows and i get notification sound. thats it i have to restart whole pc and lose 9 minutes of farm and xp or even get leavebusted... please help me :)

Oh and another problem is my client runs in 0.5 FPS i guess so i cant even ban a champion or switch runes

help me on any of theese please!