Invalid postback or callback argument. Event validation is enabled using <pages enableEventValidation="true"/> in configuration or <%@ Page EnableEventValidation="true" %> in a page. For security purposes, this feature verifies that arguments to postback or callback events originate from the server control that originally rendered them. If the data is valid and expected, use the ClientScriptManager.RegisterForEventValidation method in order to register the postback or callback data for validation.
I have enableeventvalidation set to false right now which according to some other threads is not the way to go. One person eludes to using AJAX to populate one form from the selection of another. I do have a dropdown that when the user hits the right arrow key it transfers that value to a listbox. Could that be it? I'll remove it and see what I get. Any other ideas?
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