Haven't dealt with that problem in particular, but with all obsessive behavior the trick is to interrupt the behavior and offer something more rewarding for the dog.
If you rely on her running in the yard for her exercise requirements (and it sounds as if she's getting plenty) you might try snapping a leash on her and taking her for a walk when she begins to run around. You might even try giving her a backpack with a small amount of weight in it so she feels like she's doing a job, which will re-direct her mind from "I don't know what I'm supposed to do so I'll run in circles" to "My job is to carry this back pack while we go on our walk." It's weird, but I've seen a lot of dogs react so positively to the back pack idea...especially dogs that have been bred to perform certain tasks but are only required to sit around all day.
I wouldn't give her a lot of attention while she's running around, but I would try to stop it as soon as you can and take her inside for awhile, or for a walk on the leash or do whatever you can to take her away from the area where she does it. If she runs herself to exhaustion, it's certainly not good for her and anything you can do to totally remove her from the situation long enough to re-direct her attention would help.
You will still have to deal with what triggers the behavior, and help her learn how to appropriately respond to people, dogs, bunnies etc. Spending time in the yard with her while she's on a leash might help. When she sees something and wants to run, you will be able to control her and help her learn to respond calmly (or not at all). She can work off the extra energy by chasing balls for you when she does well. | 
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