System Restor comes up with blank screen

Working on a Windows XP laptop that wouldn’t allow hotmail e-mail or college e-mail to display. It worked fine until now college installed adaware. Checked that pop-up blocker was not on. Thought I would just use system restore to go back to a week ago, however, when I try to open system restore, I just get a blank white box. What could be wrong with system resore?