ui/hotbar lockup

Several times over the last few days, Ive been having issues where my hotbar skills suddenly become unavailablevia clicking on their icons or via the hotkey shortcuts. Ive seen this several times and I am not under the effects of a condition like silence or being interrupted where it would normally prevent me from using the skills. It seems to resolved after several seconds but once it occurs it tends to recur frequently. It most frequently occurs in instances from what I can see. A few people Ive talked to have seen this happen. Has anyone else noticed this?