@ hollib I had a look at your themes
http://www.thesevensblog.com/wp-content/themes/ lists them all
mostly showing very old dates so it is not obvious which the new themes are
http://www.thesevensblog.com/wp-content/themes/azpismis/ is where your current theme is azpismis/ shows as 16-Dec-2008 11:23
There are no other themes showing with 2008 dates so you may have loaded them in the wrong folder or perhaps you deleted them? So itdoesn't show the other 9 themes you mention.
I'd say have a double check of your version 2.7 upgrade & make sure you have
followed the instructions there.
A quick look at http://www.thesevensblog.com/wp-includes/ shows lots of old dates on the files.
You needed to delete your old wp-includes and wp-admin directories & upload the newe folder / new files.
Looks like you haven't done this for /wp-includes/ and probably the wp-admin folder either.
My guess is that you have only added new files and not deleted those two folders according to the standard upgrade instructions which means you are not running WP 2.7 with all the latest files.
Consequently some of the files location calls may have changed and the templates won't load correctly because they are "looking" in the wrong place.