Then my old friend "Yellow Screen of Death" reared his, quite frankly, ugly head and started hurling abuse at me for defining duplicate sections. He has no subtlety.
Well he is lieing! I have not added duplicates. This ungoogleable problem was causing me grief because of some complete falsity. I removed the "duplicate" from the web root web.config and then it had a problem with the next defined section. Then the next and the next. I removed them all and then it got its knickers in a twist about something else.
Time to take a step backWhat am I trying to do? Run a .NET4 application from a .NET2 runtime... oh right... yeah.
I stopped my quest and started a new site in IIS for this MVC2 application, now all is well. Those errors were complete red herrings though and I suppose my head wasn't quite in gear since it was late on a Friday and there was drinking to be done!