I tested the behavior when clicking on the Upload button in the following online demo under IE6:
but I could not reproduce the problem, the dialog for uploading files opens as expected - please see the attached screenshot which shows the result on my side.
In case you still experience the problem, please open a new support ticket and send me a sample, fully runnable reproduction demo along with detailed reproduction instructions and explanations and I will do my best to help.
the Telerik team
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