I've used the following in web.config

```
<pages enableEventValidation="false">

```

This corrects a problem we've been having with Ajax.

We have a web page that if you browse to directly using a standard HTML hyperlink works fine.

If you browse to the page from another page via link inside a gridview and response.redirecting in the RowCommand event to the page passing an ID in the querystring. The page throws errors from controls inside the panel stating 

"Invalid postback or callback argument. Event validation is enabled using 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'm happy to leave the page validation as false as it seems to have had no other effect.

Any ideas what's happening?