I have isolated the RadMenu demo page with the XMLDataSource
in a simple page, but I was not able to reproduce the described unusual issues. Please find attached the project I tested, add the Telerik assembly files in the "bin" folder and give it a try at your side. Let me know if it works by you.
If you still have problems, I would advise you to start new support ticket and send us runnable project, which we can run and test.
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