Are you using SQL Express? If so, the database may be offline. You should find errors in the application log. Is umbraco application pool available to connect to the database? This error is often associated with security, so providing "you need to enable this and that" would be very useful for a hacker. Check permissions for the application pool account. Check if Mcaffee is installed - it has the habit of denying access. Try connecting with SQL authentication to see if its role. Copy and paste the connection string from the SSMS connection dialog into the web configuration of the application. Typosis is a given. At least now you know why the message is useless! PS there is an article with screenshots on the ISS umbraco installation,it can serve as a cross referencehttp://www.ava.co.uk/support/faq/umbraco/install-umbraco-4042-windows-server-2008-iis-6-sql-2008-r2.aspx