I updated a multisite site from 3.05 to 3.1.1
All of the existing sub-blogs point to the correct dashboard. One blog, however, points to the primary site's backend. If I type the correct folder in the address bar the correct backend does open.
The offending blog seemed to be made the primary blog by default in the upgrade to 3.1.1. I changed the primary site to the correct site, but this did not fix the problem.
In the same blog moving widgets around does not show the changes on the blog.