Andy, is your profile signature "iMac (27-inch Mid 2010), Mac OS X (10.7.5)" still correct or has your system changed since you set it up?
the Aperture database that is under Media - Photo is the wrong one
This may be a problem of a wrong entry in the Aperture preferences file. The Media Browser will use the most recently opened Aperture library . Try first to switch to a new empty Aperture library and then back (you can switch using the File menu in Aperture (File > Switch to Library > Other/New). Then restart your Mac to ensure, that all applications terminate properly.
If you are running Aperture 3.5.1 in Mt. Lion or later, you may need to enable the option "Share XML with other applications" in the Aperture preferences "Preview" tab. This is only necessary for non-Apple apps (Aperture 3.5: Set "Share XML with other applications" to "Never" for better performance and faster quit times).
If that does not correct the Aperture library in the Media Browser, quit Aperture and remove the "com.apple.Aperture.plist" file from the Preferences folder as described in Aperture 3: Troubleshooting basics.
-- Léonie