You have installed .Net Framework 3.5 SP1 on the machine?

Did you add default.aspx as a content page on the Document tab of the web site Properties?

If you did then make certain you unselected the "show friendly http error messages" checkbox from Tools->Internet Options->Advanced in IE. Not 100% certain where you would find this in FF or Chrome.

This will give you the "real error message" as opposed to the generic default when you re-access the site.

Also, make certain you have correct permissions on your web site folder and child folders and SQL:

Network Service - FULL CONTROL

ASP.NET or IUSR OR a specific custom account registered in Windows- Read & Execute, List Folder Contents, Read

Hit the site again and post the page output back to this thread. Please save it as <filename.txt>  in a text editor first to strip out all the nasty html white spacing, etc.