The latest official Telerik UI version for Q1 2011 is actually 2011.1.519 version (i.e., Q1 2011 SP2 release). It seems that you are using an internal build of Q1 2011 SP2. The jQuery used in Q1 2011 SP2 is version 1.5.2. More information on the used jQuery versions in Telerik UI controls is available in the Using jQuery
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