Padding is invaild and cannot be removed

[mjweiner]

I have an ajax.asp.net application that is running very well, however,
my error log is continuing to fill with "padding is invalid and cannot
be removed" These errors report that the url with the error is
http://www.mysitename.com/ScriptResource.axd?d=[different query string
each time]

Here is a sample of what is returned:
Error Message: Padding is invalid and cannot be removed.
error Source: mscorlib
targetSite: DecryptData
Stack Trace:
at
System.Security.Cryptography.RijndaelManagedTransf orm.DecryptData(Byte[]
inputBuffer, Int32 inputOffset, Int32 inputCount, Byte[]&
outputBuffer, Int32 outputOffset, PaddingMode paddingMode, Boolean
fLast) at
System.Security.Cryptography.RijndaelManagedTransf orm.TransformFinalBlock(Byte[]
inputBuffer, Int32 inputOffset, Int32 inputCount) at
System.Security.Cryptography.CryptoStream.FlushFin alBlock() at
System.Web.Configuration.MachineKeySection.Encrypt OrDecryptData(Boolean
fEncrypt, Byte[] buf, Byte[] modifier, Int32 start, Int32 length,
Boolean useValidationSymAlgo) at
System.Web.UI.Page.DecryptString(String s)
--------------------------------------------------------------------------------
queryString: d:L95-
M7qWbZMBbXmabf5PWx3fNmkgQWMFBv1RzXuSwtN2JEE0DfXgC9 QntyODxHxwhZ8-
GkJn_QWrfoxAZFjZGg2
t:633072973801159573

I am not running this on a server farm and have changed the <machine
keyin my web.config without effect. Anyone with any thoughts on
what is causing this error?

thanks,

Matt