Error Installing DotNetNuke

Which sql server are you using? SQLExpress or SQL2005.

In the first part you have the sqlexpress connection string commented out and in the second part you have both connection strings enabled.

Only use the connection string for the sql server you are using.

If it is sqlexpress and you have installed sql express, you do not need to do anything else.
If you are using SQL2005, you have to create your database, add a user/password to the database you created, then put those paramaters into your sql2005 connection string.

If everything else is set up right ,your web.config(open in notepad and edit these lines) for 2005 express should be uncommited and 2000/2005 should be commited out.

<!-- Connection String for SQL Server 2005 Express
    <add
      name="SiteSqlServer"
      connectionString="Data Source=.\SQLExpress;Database=your database;User ID=your user ID;Password=your password;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Database.mdf;"
      providerName="System.Data.SqlClient" />-->

Delete the commit out arrows and type by hand the database info highlighted. Once your done do the same for the "<appSettings>".

Final result will look like this:

 <connectionStrings>
  <!-- Connection String for SQL Server 2005 Express -->
  <add name="SiteSqlServer" connectionString="Data Source=workstation\SQLExpress;Database=your database;user ID=Your user id;Password=your password;Integrated Security=True;User Instance=True;AttachDBFilename=|DataDirectory|Database.mdf;" providerName="System.Data.SqlClient"/>
  <!-- Connection String for SQL Server 2000/2005
    <add
      name="SiteSqlServer"
      connectionString="Server=(local);Database=DotNetNuke;uid=;pwd=;"
      providerName="System.Data.SqlClient" />
   -->
 </connectionStrings>
 <appSettings>
  <!-- Connection String for SQL Server 2005 Express - kept for backwards compatability - legacy modules   -->
  <add key="SiteSqlServer" value="Data Source=workstation\SQLExpress;Database=your database;User ID=your user id;Password=your password;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=;"/>
    -->

So add in your your name ,your database, and your password in the highlight areas and commit out the connection strings around the connection string for both sql 2000/2005 settings. Remember not to copy and paste because you could get white space in the code and it will result in an error. Save your webconfig and back it up. Good luck!