My install was in its own folder until a few days ago. I moved it all to root in order to use the network feature. The move was interesting but seemed to be up and running fine once I figured out my permalinks were were making it act a little wonky.
The install used to be in the http://www.sitename.com/blog folder. I tried to set up the network feature when 3.0 dropped and realized that I would need to move my whole install in order to get it to work. Does the /blog folder need to be empty now? That would seem like a weird problem but Ive seen stranger things.
I am not sure what other info would be useful other than the site itself.
you can see one of the pages here
Thanks for the reply and let me know if any other info would be helpful.