Scrambled Fonts: GNU Emacs 23.1.1 on Ubuntu 10.04 LTS - Lucid Lynx

[bebop52 <gruenderteam.berlin@googlemail.com>]

I use Ubuntu 10.04 LTS - Lucid Lynx (with gnome) and GNU Emacs 23.1.1
(i486-pc-linux-gnu, GTK+ Version 2.20.0)  of 2010-03-29 on rothera,
modified by Debian.
Especially (but not exclusively) using the eshell, sometimes suddenly
the emacs fonts become scrambled and unreadable.
The problem remains when starting with emacs -q or emacs -Q.  Until
now the problem only shows up with emacs and no other software.
It's getting better doing this:

""
Try running these commands in the terminal, and then restart the X-
server:
Code:
sudo dpkg-reconfigure fontconfig-config
sudo dpkg-reconfigure fontconfig
""

After installing new software the problem comes back and I have to
repeat fontconfig. But even without new installs after a while the
problem shows up again.
Whats the problem and how to solve it? Any ideas would be highly
appreciated, since I only changed from XP to Ubuntu to concentrate on
Emacs, and now Emacs doesn't work reliably.