the japanese surely don't have, or rather should not have, white boxes on japanese web sites when using japanese systems, but apart from that, your problem sounds interesting.
did you do an upgrade recently, or any idea what may have caused this? on a system where no big changes are made (i.e. nothing that needs root privileges) it sounds very strange that something like that could happen just like that. if you did a system upgrade recently, see which packages got upgraded -- maybe qt, X or some libraries were among them?
your
/etc/xorg.conf file lists some font directories. there should be font files inside; if this is not the case, you will have problems
but if you have red X's on your screen here and there it could be more difficult than that..if you can, try and guess what may have happened after your system last time worked, it really might help solving this out.