What is going on?

So I will just be in a game of league and I my cursor will turn into a red attacking sword. Like when you press a, and then click. But it will stay there forever and I can't get it off. I can't press any buttons or escape so I have to force quit the game every time it happens. It's really annoying because I get behind in lane and I will usually feed and kill away because I can't run while having the attack option on. It will just auto attack.