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I've managed to reproduce this, I've log it under:
Bug 107830: ResultsViewer crashes when attempting to open results in XP
We will develop a fix for this issue ASAP.
Meanwhile, some workarounds:
-the problem only occurs on XP, if possible switch to a Windows 7 machine
-you can run your test directly in Visual Studio from the Test View. The results that will be generated will be a in a different format and you'll be able to open them
-the .aiiresult file is actually an xml - you can open it in a simple notepad
Please let me know if you have any other questions!
the Telerik team