X display errors on some programs preventing them from opening

[Claude Jones <cjoneslists tehogeeservices com>]

Firefox, Yumex, among others are not opening (kind of makes it hard to Google 
for help);  running from the icon, I just get a long initial display of the 
icon in the panel, then it vanishes and the program never opens; running from 
the command line, I get this output (in part):
*************************************************
yumex
The program 'yumex.pyc' received an X Window System error.
This probably reflects a bug in the program.
The error was 'BadName (named color or font does not exist)'.
*************************************************
I googled this from a different machine and found a lot of references to xfs 
being deprecated, and turning it off; I tried turning it off with chkconfig 
and restarting X, but no joy

Does anyone know what I might try next?
-- 
Claude Jones
Brunswick, MD, USA