Hi all,

Have any body ever seen this problem before? I went to microsoft website but not much help there. Any solution for this problem?

Thanks

John


/************************************************** **************
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)
   System.Web.UI.LosFormatter.Deserialize(String input)

[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)
   System.Web.UI.Page.LoadPageStateFromPersistenceMed ium()

[HttpException (0x80004005): Invalid_Viewstate
    Client IP: 127.0.0.1
    Port: 1199
    User-Agent: Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1; SV1; .NET CLR 1.1.4322)
    ViewState: QxNTI2NjIzO3Q8O2w8aTwxPjs+O2w8dDw7bDxpPDU+O2k8Nz47 aTw5PjtpPDExPjtpPDEzPjtpPDE1Pjs+O2w8dDxwPHA8bDxUZX h0Oz47bDxRdWFuZyAgICAgICAgICA7Pj47Pjs7Pjt0PHA8cDxs PFRleHQ7PjtsPDgzMjIyOC0yNjYyICAgIDs+Pjs+Ozs+O3Q8cD xwPGw8VGV4dDs+O2w8Jm5ic3BcOzs+Pjs+Ozs+O3Q8cDxwPGw8 VGV4dDs+O2w8Jm5ic3BcOzs+Pjs+Ozs+O3Q8cDxwPGw8VGV4dD s+O2w8MDAxOz4+Oz47Oz47dDxAMDxwPHA8bDxQYWdlQ291bnQ7 XyFJdGVtQ291bnQ7XyFEYXRhU291cmNlSXRlbUNvdW50O0RhdG FLZXlzOz47bDxpPDM+O2k8Mz47aTw5PjtsPD47Pj47Pjs7Ozs7 Ozs7Ozs+O2w8aTwwPjs+O2w8dDw7bDxpPDI+O2k8Mz47aTw0Pj s+O2w8dDw7bDxpPDE+O2k8Mj47aTwzPjtpPDQ+O2k8NT47aTw2 PjtpPDc+Oz47bDx0PHA8cDxsPFRleHQ7PjtsPDE7Pj47Pjs7Pj t0PHA8cDxsPFRleHQ7PjtsPE5ndXllbiAgICAgICAgIDs+Pjs+ Ozs+O3Q8cDxwPGw8VGV4dDs+O2w8SGEgICAgICAgICAgICAgOz 4+Oz47Oz47dDxwPHA8bDxUZXh0Oz47bDw4MzItODc3LTk5ODgg ICA7Pj47Pjs7Pjt0PHA8cDxsPFRleHQ7PjtsPCZuYnNwXDs7Pj 47Pjs7Pjt0PHA8cDxsPFRleHQ7PjtsPGgxMDdAeWFob28uY29t Oz4+Oz47Oz47dDxwPHA8bDxUZXh0Oz47bDwwMDE7Pj47Pjs7Pj s+Pjt0PDtsPGk8MT47aTwyPjtpPDM+O2k8ND47aTw1PjtpPDY+ O2k8Nz47PjtsPHQ8cDxwPGw8VGV4dDs+O2w8Mjs+Pjs+Ozs+O3 Q8cDxwPGw8VGV4dDs+O2w8SG8gICAgICAgICAgICAgOz4+Oz47 Oz47dDxwPHA8bDxUZXh0Oz47bDxRdWFuZyAgICAgICAgICA7Pj 47Pjs7Pjt0PHA8cDxsPFRleHQ7PjtsPDgzMjIyOC0yNjYyICAg IDs+Pjs+Ozs+O3Q8cDxwPGw8VGV4dDs+O2w8Jm5ic3BcOzs+Pj s+Ozs+O3Q8cDxwPGw8VGV4dDs+O2w8Jm5ic3BcOzs+Pjs+Ozs+ O3Q8cDxwPGw8VGV4dDs+O2w8MDAxOz4+Oz47Oz47Pj47dDw7bD xpPDE+O2k8Mj47aTwzPjtpPDQ+O2k8NT47aTw2PjtpPDc+Oz47 bDx0PHA8cDxsPFRleHQ7PjtsPDM7Pj47Pjs7Pjt0PHA8cDxsPF RleHQ7PjtsPERhbmcgICAgICAgICAgIDs+Pjs+Ozs+O3Q8cDxw PGw8VGV4dDs+O2w8SHVuZyAgICAgICAgICAgOz4+Oz47Oz47dD xwPHA8bDxUZXh0Oz47bDwyODEtNTMwLTY1NzUgICA7Pj47Pjs7 Pjt0PHA8cDxsPFRleHQ7PjtsPCZuYnNwXDs7Pj47Pjs7Pjt0PH A8cDxsPFRleHQ7PjtsPCZuYnNwXDs7Pj47Pjs7Pjt0PHA8cDxs PFRleHQ7PjtsPDAwMTs+Pjs+Ozs+Oz4+Oz4+Oz4+Oz4+Oz4+Oz 4m3xAHRzY8nZGVSC+wwcvuSBQzjQ==
    Http-Referer: http://localhost/Web01/main.aspx
    Path: /Web01/Contact/UpdateContact.aspx.]
   System.Web.UI.Page.LoadPageStateFromPersistenceMed ium()
   System.Web.UI.Page.LoadPageViewState()
   System.Web.UI.Page.ProcessRequestMain()

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

Check this link it may help you
http://support.microsoft.com/default...1150#appliesto