The problem that you describe sounds like the problem in Silverlight 2 (the bug is that you cannot have ItemsControl with Popup in the template and this popup to hold the items of the ItemsControl - this is the case with RadMenuItem). One solution is to avoid setting x:Name
attribute on the RadMenuItems.
But the problem may be different so if you could send us simple project demonstrating this issue it will be of great help.
the Telerik team
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