Random times where command input doesn't respond

Say for instance I was playing Xerath and I start charging my Q, and suddenly I release it, but it keeps charging and eventually cancels. Then it keeps walking in the direction I was aiming and won't respond to me clicking backwards, causing me to wander haphazardly into turrets or the enemy trying to siege.

I notice after it fixes itself that I hear a weird beeping everytime I try to do something else and then it returns to normal.

The actual hell is that?