[plt-scheme] no text in drscheme

I don't know if this is a DrScheme issue or if it's a FreeBSD/X issue, so I 
hope you'll indulge the cross-post.

I recently did an upgrade of several ports on my system, DrScheme being one 
of them.  Now when I run it, there is no visible text in any of the menus 
or dialog boxes.  The buttons and other controls are there, just sans text.  
Has anyone ever seen this before?  Any ideas for what I could check?

The version of drscheme on my machine now is 206p1.  I'm running FreeBSD 
5.2.1-RELEASE-p3.  I don't know exactly which software upgrade caused 
drscheme to stop working, but it has worked previously on this machine, and 
I haven't noticed problems in any of the other X apps I use (though that 
isn't very many).

Another interesting point is that the same thing happens if I try to run an 
older version of drscheme from a school computer (i.e. ssh -X hostname 
drscheme).  From the terminal of the remote computer, drscheme works just 
fine.

Any ideas greatly appreciated.

Thank you,

JN