Is it possible that you are suffering from an effect that prevents action. I know that I've been hit by such effects and am unable to move or perform an action until the effect wears off.
It has been happening to me all the time since about 2 days ago (versus it happening maybe twice before then). I get stuck in combat and can't use skills, block, auto-attack, use potions, or dodge. The only keys still functioning are the movement keys. 50% of the time I get kicked out due to the message rate exceeded error once the server catches up and responds (by then I am already dead anyway).
Whatever they broke, they need to fix it.
@ZOS: Also noticing a "disarming effect" where I get hit and I get stuck in a "permanent walk" can't sprint, dodge by double tapping w,s,a,d; etc. and the only solution is logging out and back in. Latest happened last night, failed taking down Molag Bal and got stomped when titans spawned during the final battle 3 times in a row. Best way to describe how it looked:The only keys still functioning are the movement keys.