For a while now I've had this problem that my Aperture Library icons will all of a sudden go “blank”, that is the library name (text) is there but there is no icon with it at ALL. This is true for all views in the finder and across several drives. Vault files are unaffected.
Usually (always can't recall a reboot will fix the problem). Any ideas as to what is causing this?!
Late 09 iMac i7 2.8GHz
OS X 10.8.2
iPhoto 8.1.2 (if that matters)