Hi Jose,
This is a known problem, especially on newer distros such as FC6 where a recent version of fontconfig library is used. You can do the following as a temporary workaround:
As root, open the fontconfig configuration file located at /etc/fonts/fonts.conf, and find two cachedir elements near the top of the file. Either comment them out or delete them, and save the file.
This problem is fixed in the next major release of SlickEdit.
Hope this helps.
Kohei