Strange unhandled exception from asp.net application - Validation of viewstate MAC failed

Question

I don\'t know if anyone has seen this issue before but I\'m just stumped. Here\'s the unhandled exception message that my error page is capturing.

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Answer 1

@Chris

if the problem is clicking an item before the page has completely rendered, asp.net 3.5 SP1 added a web.config entry on the page element called renderAllHiddenFieldsAtTopOfForm.