Definitely not the message you want to see after paying a whole lot of bucks. This happened to a colleague of mine when he tried to setup "My Sites". In fact, same error message was thrown whenever he tried to use any feature of "MOSS Enterprise".
After opening MS ticket and much debugging, here is the solution:
- Open the associated web.config
- Make any change and undo it
- Save the web.config
Believe it or not that is your solution. Hope this helps to somebody.