Font (or color) problem on current unstable x86 box

[David Goodenough <david.goodenough@btconnect.com>]

One of my machine, which I keep reasonably current on unstable, recently
started behaving a little oddly.

Several programs (the first was the new Eclipse Galileo, then IceWeasel and
now a locally compiled version of zenmap v5) have started to come up with
an error:-

The program 'zenmap' received an X Window System error.
This probably reflects a bug in the program
The error was 'BadName (named color or font does not exist)'.
  (Details: serial 154 error_code 15 request_code 45 minor_code 0)

Looking in .xsession_errors I see:-

X Error: BadName(named color or font does not exist) 15
  Major opcode: 45 (X_OpenFont)
  Resource id: 0x3c00053

So I guess I am missing something, but the question is what, and how
do I go about finding out what is missing (the messages above is not 
very helpful)?  The second message tends to suggest font not color,
but how do I translate the Resource id into something that tells me
which font is missing?

Thanks for any pointers

David