WP MU signup Redirect to edit.php

Can anybody give me advice how to fix the following instance:
It might have something to do with the new plugins in Admin, but after a while installing a few plugins from the admin area, I get a signup page
If I use my admin password it fails to login. when a hit back I am still signed in but cant use the new plugin function until later. This also happened yesterday when I tried to edit a post. it gives me the same URL