Hello again Vessy,
I have done some more investigation here. I will try to give you some contextual information. We have a page with a popup control and a RadGrid. The popup is hidden until a button on the page is clicked. The popup control contains some Rad controls. Anyway, the problem may be reproduced reliably as follows.
- Click the button to make the popup appear.
- Click cancel to close the popup.
- Now click on the RadGrid. The exception is then thrown.
Step 3 will cause the current page to redirect to another page. It seems that when the browser is forced to navigate away from the current page then the exception is thrown.
I have found that the exception is only thrown when the popup has been displayed. So, I thought that it was caused by one of the Rad controls on the popup potentially. However, I have commented all the controls on the popup out and the exception is still being thrown if I follow steps 1 to 3 above.
I have attached the Java Script stack trace as an image. Maybe that will be some use to you.
Let me know what else I can provide. Actually, would it help if I provided all the markup for the page? If so, I would like to do so privately if possible.