Well, as I said, you were the first to report such problem and so far, I am basically guessing what might be wrong :)
Could you please post the exact steps (in code) that cause the problem? e.g. something like:
- a button in the content page is clicked and calls this serverside / client-side function
- the next step fires this code
- the last step causes the resulting error.
This might help me provide you with better suggestion.
What I can say for now is that I assume you are referring to this demo
What this function does is to fire a function (refreshGrid()) in the context of the parent page and to close the RadWindow after that. This logic is not causing any problems in our demos and in IIS, so I assume that in your case, there is something else. What I would suggest (again "a shot in the dark" I'm afraid) is to change the logic a bit and if you use that RadWindow only to update a record in the grid - to call the refreshGrid() function directly from the parent page when the RadWindow is closed.
To do that, you can use the OnClientClose property and set there the name of the function you wish to fire once the RadWindow is closed.
the Telerik team