Does she behave similarly if she's left behind outside? Is she quieter in the stall of there are other horses in the barn? Some horses are really herd bound, and others have no problems that way but are really anxious and uncomfortable in a stall situation. It sounds like yours is more herd bound.
To tackle the herd-bound problem, I would work her close to her "buddies," where she wants to be. Lunge her if you can, or ride her, just keep her feet moving fairly energetically. When she is focused on you and responding to your requests, trot her to the barn and put her in the stall, and let her rest there. You can pet her, talk to her, calm her, but if she would rather be with the other horses, cool. Pull her out of the stall and take her where she wants to be, then work, rest in the stall. In the stall, you can have hay and water available to her and allow her to eat or drink if she wants, whatever she wants to do to be comfortable. She'll eventually learn that it's a lot more work to be with her buddies than it is to be by herself. When she's at least somewhat calm away from her buds, I would say start feeding her regular meals away from the other horses.
You can start by just resting outside and away from her "buddies" if she's really giving you trouble. This method also is helpful for trailer loading (work outside, rest inside).
I hope that was somewhat helpful, good luck!
A stubborn horse walks behind you, an impatient one in front of you, but a noble companion walks beside you ~ Unknown