System.Web.HttpException: Unable to validate data.

Server Error in '/' Application.
--------------------------------------------------------------------------------

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.MachineKeySection.EncryptOrDecryptData(Boolean fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length, Boolean useValidationSymAlgo, Boolean useLegacyMode, IVType ivType, Boolean signData) +1081
   System.Web.UI.Page.EncryptStringWithIV(String s, IVType ivType) +120
   System.Web.Handlers.AssemblyResourceLoader.FormatWebResourceUrl(String assemblyName, String resourceName, Int64 assemblyDate, Boolean htmlEncoded) +51
   System.Web.Handlers.AssemblyResourceLoader.GetWebResourceUrlInternal(Assembly assembly, String resourceName, Boolean htmlEncoded, Boolean forSubstitution, IScriptManager scriptManager) +1644
   System.Web.Handlers.AssemblyResourceLoader.GetWebResourceUrl(Type type, String resourceName, Boolean htmlEncoded, IScriptManager scriptManager) +722
   System.Web.UI.ClientScriptManager.GetWebResourceUrl(Page owner, Type type, String resourceName, Boolean htmlEncoded, IScriptManager scriptManager) +167
   System.Web.UI.ClientScriptManager.RegisterClientScriptResource(Type type, String resourceName) +67
   System.Web.UI.WebControls.BaseValidator.RegisterValidatorCommonScript() +215
   System.Web.UI.WebControls.BaseValidator.OnPreRender(EventArgs e) +69
   System.Web.UI.Control.PreRenderRecursiveInternal() +103
   System.Web.UI.Control.PreRenderRecursiveInternal() +175
   System.Web.UI.Control.PreRenderRecursiveInternal() +175
   System.Web.UI.Control.PreRenderRecursiveInternal() +175
   System.Web.UI.Control.PreRenderRecursiveInternal() +175
   System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint) +2496

--------------------------------------------------------------------------------
Version Information: Microsoft .NET Framework Version:4.0.30319; ASP.NET Version:4.0.30319.1

是什么原因啊  怎么修改啊  查了好多都不行啊 --------------------编程问答-------------------- 在Web.Config文件中配置

EnableViewStateMAC=false

试试看 --------------------编程问答-------------------- 试了不行啊

补充：.NET技术 ,  .NET技术前瞻