It seems that there is a java script error on your template (either from the master page or from some custom control) which breaks page editor. Can you please let us know what kind of master page and custom controls you have on the page.
the Telerik team
Registration for Q1 2011 What’s New Webinar Week is now open. Mark your calendar for the week starting March 21st and book your seat
for a walk through all the exciting stuff we ship with the new release!