This could be caused by bad HTML within the Department Description.

To strip out the bad HTML navigate to:
  1. Core
  2. School
  3. Departments and Courses
  4. Find the Department Name
  5. Click Edit on the Department Name
  6. Click HMTL​User-added image
  7. In the HTML strip out all the Div Tags and the Breaks, you can insert spaces manually by pressing Enter
  8. Click Update
  9. Save and Close the Edit Department Window