Here is the error from the 6th try...

System.Data.SqlClient.SqlException: A connection was successfully established with the server, but then an error occurred during the login process. (provider: Named Pipes Provider, error: 0 - No process is on the other end of the pipe.) at System.Data.ProviderBase.DbConnectionPool.GetConnection(DbConnection owningObject) at System.Data.ProviderBase.DbConnectionFactory.GetConnection(DbConnection owningConnection) at System.Data.ProviderBase.DbConnectionClosed.OpenConnection(DbConnection outerConnection, DbConnectionFactory connectionFactory) at System.Data.SqlClient.SqlConnection.Open() at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, CommandType commandType, String commandText, SqlParameter[] commandParameters) at Microsoft.ApplicationBlocks.Data.SqlHelper.ExecuteReader(String connectionString, String spName, Object[] parameterValues) at DotNetNuke.Data.SqlDataProvider.GetDatabaseVersion() at DotNetNuke.Data.SqlDataProvider.GetVersion() at DotNetNuke.Services.Install.InstallWizard.get_DatabaseVersion() at DotNetNuke.Services.Install.InstallWizard.TestDataBaseInstalled() at DotNetNuke.Services.Install.InstallWizard.Initialise() at DotNetNuke.Services.Install.InstallWizard.OnLoad(EventArgs e) at System.Web.UI.Control.LoadRecursive() at System.Web.UI.Page.ProcessRequestMain(Boolean includeStagesBeforeAsyncPoint, Boolean includeStagesAfterAsyncPoint)

None of the errors Ive seen you reporting seem to relate to dnn - all these errors seem to be related to how your system is setup.
Firstly to permissions and now to the way you have ms sql setup.  

The reason this message appears is because of the web.config connectionString that you are trying to use.
Integrated security is not ideally supported across network connections using tcp-ip - and is really only suitable
to direct server connections on local machines.

Rather than using the default authentication details of ms Integrated Security=True you should use ms sql server authentication.

So instead of:

connectionString="Data Source=myserver\SQLSERVER2005;Initial Catalog=dnnDatabase;Integrated Security=True;"

Use "User ID=sa Password=test"  for example in the connection string:

connectionString="Data Source=myserver\SQLSERVER2005;Initial Catalog=dnnDatabase;User ID=sa;Password=xxxxxxx;"

Its really just not that difficult - Ive setup hundreds of dnn sites over the years with little of no issues - as have most of the million plus users of dnn downloads.

Since you are having these sort of issues with your system - you should be using the ms web platform installer version - it will take control of all the system settings - which seem to be incorrectly setup -- download it here and hit run - about 10mins latter you will have a fully installed and configured dnn site running on your computer - the link to it is here -  http://www.microsoft.com/web/gallery/install.aspx?appid=dotnetnuke_iis .

Westa

MB34 unfortunately it must just be user error as I've installed a lot of versions and also upgraded the versions all without any errors at all.

If your IIS and SQL settings are set up correctly you should have no problems at all.

Don't blame the product, blame yourself.