ASP.net - The status code returned from the server was: 500

First off, I am new to ASP.net, so this is new territory for me.

I am using Telerik controls on a VB.net project. I get the following error as a javascript error for every action on the form. Changing any value, whether its a telerik slider, a radio button, asp:button, submit button, telerik rating.

Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while 
processing the request on the server. The status code returned from the server was: 500

I understand that the 500 error is an error thrown when the server doesn't have any more details, however I was hoping someone might have had a sim开发者_开发百科ilar situation and can point me the right direction as I have a good feeling it has something to do with the Telerik controls.

I was able to submit the form using javascript however then I get the following error, and I don't know if they are related or not.

Validation of viewstate MAC failed. If this application is hosted by a Web Farm or
cluster, ensure that <machineKey> configuration specifies the same validationKey and 
validation algorithm. AutoGenerate cannot be used in a cluster.

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I've had this exception a few times with telerik controls. Try using an application like Fiddler

http://www.fiddler2.com/fiddler2/

When your application gets to the point of the exception, it will give you more details.