I understand your scenario now, but still I don't know how to reproduce the problem - your setup looks pretty standard so I would recommend that you try to find the problematic component by removing the elements on your page one by one. For example - you can first remove the pagers, then you can try to simplify the ItemTemplate contents, then turn off AJAX and so on until you find what causes the problem.
the Telerik team
Register for the Q2 2011 What's New Webinar Week. Mark your calendar for the week starting July 18th and book your seat for a walk through of all the exciting stuff we will ship with the new release!