Make sure you do your sharpening at 1:1 zoom. These white lines are usually caused by over sharpening. You can only see whether you are over or under sharpening at 1:1. It can also be caused by using the brush with auto-masking enabled. That is generally not a good idea at hard edges.
It's difficult to diagnose without being able to see the image. However, a white line around a subject often is the result of too much sharpening.