CRITICAL ERROR

I am getting a error while i'm at the File Manager. I can't create new folders, upload files or anything for that matter. I get the following error...

A critical error has occurred.
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.

This was a clean install of DNN 4.0.2 and i'm using SQL SERVER 2005 EXPRESS. Everything else appears to be working well except for this File Manager page. I actually was even able to upload an image on the Settings page, just not the file manager for some reason.  Any help would be greatly appreciated!!!