I've had this happen to me in AV twice on my hunter and once on my druid. The only problem is I'm still not entirely sure how to cause it. In all cases it requires your avatar to be at the npc armor scrap quest person. My characters are all Alliance so I'm not sure if this would work on the other side.
In each instance I was already in combat with the oposing faction who was entering the base. I had tried to quest turn in my loot before they could aggro or kill them. However (this is the fun part), When they did Aggro I was in a portion of turning the quest in and it forced me to aggro as well. You WILL lose control of yoru character and WOW will take over. From this point you will start summoning multiple crystals dragonets (takes about .5 seconds to summon) and attackign the horde. Your damage to teh horde is insane and you can take a pounding (not to mention the damage your dragons cause). If you managed to push them back your char will run back and stand with the npc's for a bit and aggro any horde that come by. Eventually (not sure if its a timeing or otherwise) you will regain control of yoru character or you can do a quick relog. The only problem is if you die, your character will run back and stand where the npc's would be and still react to horde as if they were there but be uanble to truly do anything. If your corpse is there it will let you rez to continue the fight.
If anyone can get the surefire way (which portion) you have to be in to trigger this I would be appreciated
Edit: According to a poster below in this thread, it can also happen in an arena
Number of people confirming: 11 (as of 10/07/0 - Confirmed in this thread
Screenshot in Arena of same problem posted by "ROSULM" --> ImageShack - Hosting :: rekindlenw0.jpg