Gdk-WARNING **: gdk_font is NULL or not a fontset

Hi all,

I downloaded mozilla-sparc-sun-solaris2.7-1.2b.tar.gz. After gunzip and
tar -x I tried to run run-mozilla.sh. It starts up, but after a few
seconds it prints the Gdk warning (see subject) to the terminal and then
it hangs. The same happens with the 1.2a version,but there it core
dumps.

Host: SunOS costanza 5.8 Generic_108528-13 sun4u sparc SUNW,Ultra-60
Gdk: libgtk-1.2.so.0.9.1

I couldn't find any help in release notes or in bugzilla.
Any help would be appreciated.

Sven