Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster

I've read countless posts on this topic, and tried several solutions but I'm still seeing this error. I'm running iis6, .NET 2.0 on a single server. When clicking a link on my form, and new page is opened that allows the user to enter a bunch of data (it's an order form). When clicking save, I see this error:

"Validation of viewstate MAC failed. If this application is hosted by a Web Farm or cluster, ensure that configuration sp开发者_运维知识库ecifies the same validationKey and validation algorithm. AutoGenerate cannot be used in a cluster."

I've verified that the page has finished loading before clicking the save button.

I've tried:

• adding enableViewStateMac="false" to the Page directive

• adding this to the web.config <machineKey validationKey="AutoGenerate,IsolateApps" decryptionKey="AutoGenerate,IsolateApps" validation="SHA1"/>

• adding viewStateEncryptionMode="Never"in the page tag in the web.config

• adding enableEventValidation="false" in the page tag in the web.config (which I'm not sure I should do)

• adding renderAllHiddenFieldsAtTopOfForm="false" in the page tag in the web.config

And I've checked for coding errors, but everything is working fine locally. Does anyone have another suggestions? Thanks