I tried to reproduce the problem but to no avail? Could you please provide a sample page reproducing this problem so we can examine and debug it locally? Also, are you able to reproduce the problem on the live demos
For your convenience I have attached my test page. Could you please modify it to a point where the problem occurs and send it back? Also, the following video demonstrates my test, could you please see if I am doing something wrong?
On a side note, the current latest official version of RadControls for ASP.NET AJAX is Q2 2011 (2011.2.712), nevertheless, I used the version that you have pointed (2011.1.413) for my tests.
the Telerik team