Hello Mike Causi,
We will need some details regarding your scenario in order to troubleshoot the problem that you experience. Could you please answer the following:
1) What is the size of the file that you are trying to upload?
2) Which version of IIS do you use?
3) Do you use authentication/authorization enabled for your web-site?
4) Do you have the Telerik.Web.UI.WebResource.axd handler registered into your web.config?
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