Thank you for reporting this failure. It is a known issue for version 2012 Q2 (2012.2 607) and has already been fixed in 2012 Q2 SP1 (2012.2 725).
A temporal solution if you decide to continue using 2012 Q2 version of the controls (2012.2 607) will be to disable the TableMovementLayer in the following way:
MainPage : UserControl
CustomUILayerBuilder : UILayersBuilder
The concept behind UILayers is described in this article
is you are interested.
If you upgrade to the service pack, the problem should not occur even if you do not remove the layer.
I hope this information helps. Don't hesitate to contact us if you have other questions.
the Telerik team