I found solution on this page.

http://www.wains.be/index.php/2006/10/27/ubuntu-the-networkmanager-applet-could-not-find-some-required-resources-it-cannot-continue/

Solution:

sudo gtk-update-icon-cache -f /usr/share/icons/hicolor

DESCRIPTION
gtk-update-icon-cache creates mmap()able cache files for icon themes.

It expects to be given the path to a icon theme directory containing an
index.theme, e.g. /usr/share/icons/hicolor, and writes a
icon-theme.cache containing cached information about the icons in the
directory tree below the given directory.

GTK+ can use the cache files created by gtk-update-icon-cache to avoid
a lot of system call and disk seek overhead when the application
starts. Since the format of the cache files allows them to be mmap()ed
shared between multiple applications, the overall memory consumption is
reduced as well.