So find out where it is installed on your system. Mine now has[damo@cb1-laptop ~]$ locate gdk-pixbuf-query-loaders
/usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/gdk-pixbuf-query-loadersThen try using that path as the command to write the loaders.cache file
Replying to myself:I found the solution to the font msg here.And the pixbuf error msg was solved by:sudo aptitude install gtk2-engines-pixbuf But still gksu or gksudo aptitude (and others like synaptic and others as well, i'd suspect ...) do not work.
I searched for:Unable to locate theme engine in module_pathand came up with some interesting results ...one idea that stick out means reinstalling the theme you are using:sudo apt-get install --reinstall gtk2-engines
sudo apt-get install gtk2-engines-pixbuf
sudo apt-get install --reinstall gtk2-engines gtk-murrine-engine gtk-equinox-engineor what ever ...