Thank you for writing.
The best way to debug such exceptions is to download the source code attach your project to the main WinForms solution (RadControlsVS2010.sln). This way you can reference the projects and see the exact line where the exception occur. JustDecompile is helpful when you need to view the code of a compiled assembly and I don't think that it will be useful for this particular case.
In addition you can download the pdb files from your account: Download Product Files
I hope this information helps.
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