Here is a fix/workaround to the infamous message:

Could not find file '...\Website\Providers\DataProviders\SqlDataProvider\DotNetNuke_template.mdf'

By default, the "Connection String for SQL Server 2000/2005" is commented out, leaving the "Connection String for SQL Server 2005 Express" as the connection string used during site creation.

I don't know the cause, probably permissions not granted to a "default SQL user or group".

But because the Connection String for SQL Server 2000/2005 is a valid form for SQL Server 2005 Express.

This the solution I came up with:

Step 1

Start with a fresh web.config, copied from release.config

Under
  <connectionStrings>

Comment out the connection String for SQL Server 2005 Express thus :

<!-- Connection String for SQL Server 2005 Express
    <add
      name="SiteSqlServer"
      connectionString="Data Source=.\SQLExpress;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Database.mdf;"
      providerName="System.Data.SqlClient" />
  -->   
and uncomment the Connection String for SQL Server 2000/2005 thus :

    <!-- Connection String for SQL Server 2000/2005     -->
    <add
      name="SiteSqlServer"
      connectionString="Server=(local);Database=DotNetNuke;uid=;pwd=;"
      providerName="System.Data.SqlClient" />
     
Repeat steps under
<appSettings>
thus:
    <!-- Connection String for SQL Server 2005 Express - kept for backwards compatability - legacy modules  
    <add key="SiteSqlServer" value="Data Source=.\SQLExpress;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Database.mdf;"/>
    -->
    <!-- Connection String for SQL Server 2000/2005 - kept for backwards compatability - legacy modules    -->
    <add key="SiteSqlServer" value="Server=(local);Database=DotNetNuke;uid=;pwd=;"/>

Step 2

If you have followed the steps to create an empty database
and create a user with dbo role on that database then
    fill in:
    Server=NameOfYourServer;
    Database=NameOfCreatedDatabase;
    uid=NameOfUserWith_dboRole;
    pwd=PasswordOfNameOfUserWith_dboRole;
   
    under both <connectionStrings> and <appSettings>

Step 3   
     Save web.config
     If your IIS server was running, stop and start

PS

I am curious to know what configuration has to be done for the Connection String for SQL Server 2005 Express to work.

    

THIS IS A REAL HOT FIX... Many Many Thanks Milliwatt

I've been trying to install DNN for about a week now, and after running into many many problems the DoyNetNuke_template error message was the last one on the list...

I can now finally play with DNN! At last!!!!!!!