When playing (most often as melee) you'll often come across situations where when attacked your character will go through a "hit" animation, and cry out. When you do this all your attacks (normal or special) are interrupted for a short time, however if you are surrounded by enemies, as you often are as melee, this can happen multiple times in a row; effectively stun locking you to death. My question is what causes this to happen? And how can you avoid it?
Based on your comment information, it sounds like the fairly common character desync issue.
Every now and then, where your computer thinks you are, and where the server thinks you are, are in two different locations. This can be caused by several things, such as using movement abilities (Leap, Dashing Strike, Tempest Rush), or even just pausing the game in single player by hitting Escape, and then resuming later.
This causes not only the desync issue, but you'll also have trouble properly hitting enemies or avoiding damage spots, since your computer thinks you're at Point A, and the server thinks you're at Point B. This can lead to some interesting situations where you think you're attacking an enemy, but not doing any damage. Or you run out of their desecration patch, but you're still taking damage. That's because the server thinks you're still at Point B; until you re-sync with the server, you can move all you want, but the server won't actually think you're moving.
In most cases, the de-sync happens in a radius around the point where you de-synced. Leaving this radius usually causes the server and your computer to re-sync, which is your computer re-updating your position to where the server thinks you are. That's the rubberbanding happening. Rarely, this will not cause the computer to re-sync, leading to infinite rubberbanding, as you try to leave the area over and over. In cases like this, I've found that those same movement powers that can cause a de-sync will allow you to re-sync.
The vast majority of this information just comes from my observations while playing, and experimenting when hitting the de-sync issue. Once, I got de-synced while hung up on a chest; the rubberbanding was instantaneous, leading me to stutter in place. The only way out was to use Dashing Strike; that got me off the chest, and continue playing.
I have noticed this and died many times, because Revenge would not activate after pressing the key multiple times. This happens a lot because I put myself in a situation surrounded by enemies, or especially when getting hit by a ranged enemy. I assume this is because you are getting critically hit. Exactly the same as you critically hitting an enemy, any animation or attack they are activating is immediately stopped if you critically hit them. Obviously, you can counter this by stacking critical hit gear, but your barbarian skills like Overpower - Crushing Advance, Ground Stomp, Threatening Shout - Falter/Terrify and Leap will greatly minimize the occurrence, as well as any skill that has a "knock back".
Additionally, critically hitting a blue elite group has no affect in resetting their animation, but it does to unique groups and especially goblins when they are trying to flee!