Strange error

I am getting this error on post back intermittently. The error occurs only on the hosting server and not on the local development. I publish precompiled version of the site

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

any ideas??

thanks

 

You should sticky that, I totally missed it.

 

Look at this article and the comments below it:
http://aspadvice.com/blogs/joteke/archive/2006/02/02/15011.aspx