Prosites redirect when login to user site admin

When a user signs up for a new site everything works fine and the user can view their site like this http://emily.discountwebdesigner.com/. When the user tries to login to their admin account they are redirected to a page with this url http://www.discountwebdesigner.com/pro-sites.htm?bid=5

This pages content area is blank and the users cannot access their dashboards although the login seems to work because when they go back the their site the meta widget contains a logout button and the top menu shows.

Any ideas what could make this happen?