Interestingly - when I take a whole-screen screenshot (print-screen), and save it to the desktop; I get a generic "png" icon instead of a nice thumbnail.

Curiously if I touch the file from the terminal - it then re-thumbnails just fine - or if I copy a local-file there, it's ok too.

Is it possible that the screenshooter saves the file very slooowly, such that nautilus gets the notification & starts thumbnailing it before it's fully saved ? :-) [ I have a dual core machine ]. I can take some interleaved straces if people can't reproduce.