I set up the new NuGet Gallery on a web server (under IIS 7.0) where I work. The site itself is set up and runs fine. We are able to register accounts, confirm email address
I assume you're referring to the new gallery: https://github.com/NuGet/NuGetGallery
Can you try hitting /elmah.axd from an admin account and see if you get more info about the error?