Game randomly freezing??

after the latest patch playing Aram with the bilge water map every game so far i haven't been able to complete because my game freezes after like 10-15mins of gameplay i can't alt f4, task manager or anything normal to close the game and reopen it i have to sign out of my windows account on my computer and re sign in but the same thing still happens after a couple of minutes, this has never happened to me before current bug or something going on with this patch?? p.s ive already tried repairing the client still does it