When approaching a bad guy from a distance with melee classes, after pressing an attack button, as I get closer to the mob, I have noticed that occasionally the screen/character will shake back and forth really fast as you get close to your target. As if I was moving my mouse left and right very quickly. This is the case with Super Strength, Martial Arts, and Fire Melee, specifically. However, this issue did not seem to happen with the Broadsword set. It also does not seem to be limited to a specific type of bad guy.
This shaking also occurs sometimes when right clicking the 'loot' rectangle on the ground after the mob is dead.