>I am using VS2005 version 2.0.50727.3082.
>
>We have a user that is getting the following error message in his IE while using our web app.

>Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that machineKey configuration specifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster.

>
>This user does not get this error message every time. Also I have not been able to reproduce this error. I have to assume other users are getting this error message also. And I am not using a web farm.
>
>Have any other experienced this problem before? Are there any solutions or suggestions?
>
>Thanks,
>
>Jerry

Jerry,

See if this http://blogs.msdn.com/tom/archive/2008/03/14/validation-of-viewstate-mac-failed-error.aspx will help you with this question.