Page Error

System.Security.Cryptography.CryptographicException: Unknown token: 66b6b7b8
   at Kidz.Business.ACL.Encryption.Token.LoadAclToken(String encToken)
   at Kidz.Business.ACL.Encryption.Token..ctor(String encToken)
   at Kidz.Business.External.frmRSVP.get_Token()
   at Kidz.Business.External.frmRSVP.ProcessToken()
   at Kidz.Business.External.frmRSVP.OnPreInit(EventArgs e)
   at System.Web.UI.Page.PerformPreInit()
   at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)