WordPress MU

We're using WP:MU for our sites contributors, and many of these contributors are authors in multiple blogs. When I added the users, I discovered that it sent out a generic sign in to an area they have no access to. Is there anyway they can login to the the root domain and give them access to their multiple blogs?

Thanks.

Are they just authors on individual blogs and not admins of that blog? Did you just add them as users to the system, without a blog of their own?

If so, they have to sign in to each blog.

So if they are attached as the admin of at least one blog they will be able to login without the error? Or only on the blog they are admins.

We're a newspaper, so we have to regulate the blog postings, and that's why we set them up as authors and not admins.