Give her a little more time to settle in. Do you know if she was stalled at her last home? I don't think this is an issue with not having other horses, because if it was she would be pacing the side of the fence where the others are. But she is on the far side pacing the woods. She could "see something" out there. My mare will sometimes stop and stare out into the desert for no reason that I could see. The horse is probably upset by some animal that currently resides in those woods. Or she's just acting on an old habit.
Give her time.
"You can do something wrong for thirty years and call yourself experienced, you can do something right for a week and experience more than someone who spent thirty years doing the wrong thing." ~WhattaTroublemaker