It seems to be related to some font or desktop theme settings set in that configuration file.
I also noticed that the problem may come back after altering the font and theme details through the applet in System -> Preferences -> Aspect. Anyway removing the above mentioned file fixes the issue once again.
I’ve eventually figured out the issue being profile-specific and a workaround being the removal of a configuration file in your profile directory:
rm $HOME/. gconf/desktop/ gnome/interface /%gconf. xml
It seems to be related to some font or desktop theme settings set in that configuration file.
I also noticed that the problem may come back after altering the font and theme details through the applet in System -> Preferences -> Aspect. Anyway removing the above mentioned file fixes the issue once again.