@black_cat, can you have somebody watch you while you walk her, or videotape (better), and watch carefully and see if she is limping at all, or bobbing her head or anything like that, esp on the front end. The fact that she rolls over while running is also concerning. There is no reason she just wouldn't "want" to go where you want to go. It really sounds physical to me. Watch for limping, dragging a toe, head bobbing, and if you see any of that, take her to your vet and describe all that to them.