Thank you for the reply. I am actually using the RadUpload control (http://demos.telerik.com/aspnet-ajax/upload/examples/overview/defaultcs.aspx), not the RadAsyncUpload control (http://demos.telerik.com/aspnet-ajax/asyncupload/examples/overview/defaultcs.aspx?product=asyncupload), which means that I can't answer your first two questions, unless you are suggesting that I switch controls. The functionality that I need is for the user to select a file to upload, submit, then the file gets copies and some other processes, then a message displayed to the user when completed. Let me know if you think the RadAsyncUpload control would be better for my purposes? The web application has previously been working fine to my knowledge and the only major recent changes were to convert the web site to a precompiled web application and to move from framework/app pool 3.5 to 4.0.
Here is the source code for the control on the front page:
Note that I do not think that it has anything to do with the validation, since it behaves the same way when I took it out entirely.
Let me know if I can add any additional details? In the meanwhile, I sent a request to our network guys to get the fiddlercap tool. Thank you for your help!