I think most of those boarders that have problems is because they don't handle their horses enough, and too many other people are. Remember that a lot of these barns will hire the cheapest help, not the best, for basic barn chores and such. I'm not talking about the trainers or instructors, I'm talking about the people who are in and out of the stalls all day feeding, cleaning, filling buckets, etc. They may or may not have any horse knowledge at all. Horses that don't have consistent leadership may try to take over the role of alpha themselves, and begin to test those around them, including the owner that they aren't seeing as often as they are seeing the barn help.
I am more prone to think this case has more to do with boredom and too much pent up energy than being moved to a different stall, unless she is extremely nervous and high strung. It's not your fault if you have an injury that prevents you from doing anything right now. I would suggest, if you have a friend at this barn that you trust, that you might have them work with her some purely to burn off that extra energy, even if you feel you need to be there to watch to make yourself feel better about what's going on with her.
Some horses just don't do well in a stall. I have a gelding that will try to kick through the wall if left in more than a few hours, and will pin his ears and threaten any horse nearby, even those he is buddies with in the pasture. He is just not happy in a stall. In the pasture he is the sweetest and most tolerant horse we have. Having said that, he never threatens a human, or offers to bite. That is NOT okay. That's a behavior that will escalate and get someone hurt. You have to correct her sharply and quickly if she does it again. Good luck!
"Keep a leg on each side and your mind in the middle"