When i try to run the installation i get the initial screen. I choose custom, typical, or auto and i get this error no matter what i do.

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.

How do i fix this?

I am installing DotNetNuke 4.9.3 Install package and using SQL server 2005 express. When configuring the database connections I get the following error messages:

Connection Error(s):
Index#:0
Source: .Net SqlClient Data Provider
Class:14
Number:15350
Message: An attempt to attach an auto-named database for file C:\DotNetNuke3 failed. A database with the same name exists, or specified file cannot be opened, or it is located in UNC share.

Server error in '\DotNetNuke3' Application

Validation of view_state MAC failed. If this application is hosted by a web farm or a cluster, ensure that <machineKey> configuration specifies the same validation key and validation algorithm. Autogenerate cannot be used in a cluster.

By the way, I've created a database called 'DotNetNuke3' and saved it, but it is not there in C:\DotNetNuke\App_data\ -folder. I don't know why.

Where should the file web.config be situated? In different folder than default.aspx , and to where they are ok to transfer? Now they both are in C:\DotNetNuke -folder.

br, Doris