I don't know if this was a one-time fluke, or a larger problem, but after a recent update in Fedora 16, gtk based apps stopped being able to load images for me. Logging into gnome3 would give a blank blue desktop, no icons would appear, gtk based apps (e.g. inkscape) would be unable to open images, and disk utility would crash. My /var/log/messages was filled with Gtk-WARNING messages like these:
May 21 03:15:28 localhost gnome-session: Gtk-WARNING: Theme parsing error: gtk-widgets.css:841:71: Couldn't recognize the image file format for file '/usr/share/themes/Adwaita/gtk-3.0/assets/radio-menuitem-checked-selected.svg'
And starting gtk apps would complain about bad pixmaps.
After some googling and trial and error I managed to fix this. In case someone else runs into a similar problem, here's what I did:
$ su -c 'yum reinstall shared-mime-info'
$rm -rf ~/.local/share/mime
So it seems like some mime setting was corrupted somehow. Has anyone else had this problem?