Originally Posted by D

If it bothers you, let her know if bothers you, and she should limit her time on the page to breaks and such.

If she continues and disregards your sentiments, take all steps you consider appropriate - being sure to clue her in on the severity of the issue, and then ultimately, find a replacement for her.

Blocking sites, etc, only hurts morale in my experience - and that has a tendency to backfire in many different ways.