Guild Wars 2

When you get stuck with an Immobilize , for a half a second you are unable to use any 1-5 skills. Annoying bug.
I see it and experience it when hit with a LB warrior immob skill, and I am a Thief.

this is most likely from being immobilized while jumping near a non flat area of terrain or sliding down terrain, your character will be immobilized in the falling animation and u wont be able to use skills save perhaps shouts, animationless skills, and stun breaks. now if this is happening on flat ground and you are not airborn a video would be much better info