Hello lcom23,I had the same problem after upgrading my installation from 6.0 to 7.0. It appeared to be a problem with the rights that did'nt allow to really upgrade (make the installation). I had to go, in the main menu, to (sorry if the titles of the elements are not goo as I Translate it from french) "Preferences" -> "Desktop session settings" and to check the "PolicyKit Authentication Agent" line.
I hope that it helps.
