Kevin,

If you don't have a backup of your web.config file, then I suggest you download the DNN 4.x package, and re-configure and use the web.config file from there... what exactly did you change in your current web.config file? I would imagine it's the query string. Are you connecting to a database other than SQL server? If so, then you would need the appropriate data providers because DNN only gives you the data providers for SQL server. One more thing, have you given ASP Net account the appropriate security permissions to your Windows directory on your server? What is the authentication setting for your DBMS? (Tip: best practice while configuring is to change the DBMS authentication to "mixed" mode)

To troubleshoot this, please provide a little more detail 1. what were you trying to accomplish before DNN threw you an exception, 2. what changes did you make, and 3. complete description of the error.

-Nila