SERVER ERROR - UNABLE TO VALIDATE DATA

Does anyone know how to correct this? and if so... How?


Server Error in '/' Application.
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Unable to validate data.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.Web.HttpException: Unable to validate data.

Source Error:

An unhandled exception was generated during the execution of the current web request. Information regarding the origin and location of the exception can be identified using the exception stack trace below.

Stack Trace:


[HttpException (0x80004005): Unable to validate data.]
System.Web.Configuration.MachineKey.GetDecodedData(Byte[] buf, Byte[] modifier, Int32 start, Int32 length, Int32& dataLength) +195
System.Web.UI.LosFormatter.Deserialize(String input) +60

[HttpException (0x80004005): Authentication of viewstate failed. 1) If this is a cluster, edit <machineKey> configuration so all servers use the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster. 2) Viewstate can only be posted back to the same page. 3) The viewstate for this page might be corrupted.]
System.Web.UI.LosFormatter.Deserialize(String input) +118
System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +102

[HttpException (0x80004005): Invalid_Viewstate
Client IP: 69.194.58.179
Port: 1216
User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; FunWebProducts-MyWay; SV1; .NET CLR 1.1.4322; .NET CLR 1.0.3705)
ViewState: 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
Http-Referer: http://www.etobicokeci.com/newPictures.aspx 
Path: /newPictures.aspx.]
System.Web.UI.Page.LoadPageStateFromPersistenceMedium() +448
System.Web.UI.Page.LoadPageViewState() +18
System.Web.UI.Page.ProcessRequestMain() +447




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Version Information: Microsoft .NET Framework Version:1.1.4322.2032; ASP.NET Version:1.1.4322.2032