i would normally put it down to lag, but it happens even when in small fights. i've died quite a few times to it now as well.
Goes into a tower to get a sniper - agro'ed all the NPCs on the resource - fine i can reset them, meet sniper face to face - give death stare - all skills gray out - luckily sniper runs away - at leased 2 mins go by skills are still gray - sniper returns and kills me.
its happening to me very often sometimes skills are greying out for over 5 mins.
PC EU Vivec - Magwarden.