Strange Error on Logout

Hi, I'm getting a strange error usually associated with logging in and out of my application.

Error Caught in Page_Error event

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Error in:http://www.congressnow.com/ArticleDetail.aspx?articleID=3388
Error Message:Unable to validate data.
Stack Trace:
at System.Web.Configuration.MachineKeySection.GetDecodedData(Byte[]buf, Byte[] modifier, Int32 start, Int32 length, Int32& dataLength)at System.Web.UI.ObjectStateFormatter.Deserialize(String inputString)

ExceptionType: System.Web.HttpException

It may be because your machine key has changed. This usually happens when you leave a page up for a long time and the key gets updated. Take a look at this article for more information:http://support.microsoft.com/default.aspx?scid=kb;en-us;Q312906

Actually I added this little ditty to the web.config and it fixed everything right up:

<pages
enableViewStateMac="false"
enableEventValidation="false"
viewStateEncryptionMode="Never"
maxPageStateFieldLength="10"
validateRequest="false" >