W3 with Emacs in Xterm

Hi,

I installed w3 on GNU Emacs 21.2.1 and it works, when I use the Xlib
version.  But when I start it in Xterm, I get the following error:

Contacting www.cs.indiana.edu:80
Request sent, waiting for response...
Retrieval complete.
Parsed  80% of 2951...
Parsed 100% of 2951...done
Drawing... done
set-face-attribute: Wrong type argument: stringp, nil

The backtrace shows the following:

Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  internal-set-lisp-face-attribute(w3-style-face-00004 :family nil 0)
  set-face-attribute(w3-style-face-00004 nil :underline nil :weight normal :family nil)
  font-set-face-font(w3-style-face-00004 [:family nil :weight nil :style 0 :size nil :registry nil
:encoding nil])
  w3-display-node((*document nil ((html nil ...))))
  w3-draw-tree(((*document nil (...))))
  w3-prepare-buffer()
  w3-pass-to-viewer()
  w3-sentinel(#<buffer *Messages*≥)
  w3-fetch("http://www.cs.indiana.edu/elisp/w3/docs.html")
  w3()
* call-interactively(w3)
  execute-extended-command(nil)
  call-interactively(execute-extended-command)