DNN installations on our servers use the SQL Server 2005, we do not use SQL Server Express on our Shared Hosting Environments so please do not use SQL Server 2005/2008 EXPRESS connection strings.  Instead, use SQL Server 2005/2008 Connection strings.

If you do not have these, here is an example of what you should have bellow:

This one goes under <connectionStrings>

<add name="SiteSqlServer" connectionString="Server=db1.3essentials.com;Database=DBNAME;uid=DBUSERID;pwd=DBPASSWORD;" providerName="System.Data.SqlClient" />

This one goes under <AppSettings>

<add key="SiteSqlServer" value="Server=db1.3essentials.com;Database=DBNAME;uid=DBUSER;pwd=DBPASSWORD;" />