Icons problem with GNOME 2.10 (Fedora Core 4)

[Emmanuel Briot <briot adacore com>]

Hi,
I updated today from a fedora Core 2 to Fedora Core 4 system (through
apt-get dist-upgrade).
When I start my new GNOME, there are no icons displays in nautilus,
except for the default grey folder icon. Similarly, menus do not contain
any icon.
gthumb is not able to display PNG or JPG images, and gimp display a
message that "PNG" type is not supported.
The GNOME splash screen is a blank window.

I have checked, and libpng is installed on my system.
I have also restarted after removing the directories ~/.gconf*
~/.gnome*, but it hasn't changed.
The RPMs are for GNOME 2.10, from
    http://ayo.freshrpms.net fedora/linux/4/i386

lyon# apt-cache show libpng
Package: libpng
Section: System Environment/Libraries
Installed Size: 404154
Maintainer: Red Hat, Inc. <http://bugzilla.redhat.com/bugzilla>
Version: 2:1.2.8-2

Any one has ideas of things I should try ? I haven't found anything in
the archives so far, but a pointer to a "README" is certainly good enough.

Thanks in advance

Emmanuel