Game freezing on screen

So I'm having some trouble. At random intervals, usually only once in a game every few games but sometimes multiple in a row, my game freezes. No ping spike no other applications running, and it isn't my laptop freezing because my buttons still respond. However, even if I use alt+tab my screen won't leave the league match. The only solutions I've found is signing out or restarting my computer, though this only solves it for that match, and even then it will come back in the same match sometimes. I have an Acer Aspire R 15. Any thoughts would be great