Error from ps.map in GRASS. How to fix?

I'm trying to learn how to use ps.map in GRASS. I thought that running it in interactive mode from the command line would be a good place to start, but I'm getting the following error:

> ps.map                                                                                 ~
Traceback (most recent call last):
  File "/Applications/GRASS-6.4.app/Contents/MacOS/etc/wxpython/gui_modules/menuform.py", line 59, in 
    import globalvar
  File "/Applications/GRASS-6.4.app/Contents/MacOS/etc/wxpython/gui_modules/globalvar.py", line 76, in 

    import wx
  File "/Applications/GRASS-6.4.app/Contents/MacOS/etc/python/wx/__init__.py", line 45, in 
    from wx._core import *
  File "/Applications/GRASS-6.4.app/Contents/MacOS/etc/python/wx/_core.py", line 4, in 
    import _core_
ImportError: dlopen(/Applications/GRASS-6.4.app/Contents/MacOS/etc/python/wx/_core_.so, 2): no suitable image found.  Did find:
    /Applications/GRASS-6.4.app/Contents/MacOS/etc/python/wx/_core_.so: mach-o, but wrong architecture

UPDATE: In response to Markus's comment that terminal messages on GRASS startup might help to diagnose the problem, the following two chunks provides all terminal output from GRASS startup.

Chunk 1: from starting /Applications/Grass-6.4.app to GUI Startup window.

Last login: Sat Mar 23 10:08:40 on ttys002
gregory@Gregorys-MacBook> '/Applications/GRASS-6.4.app/Contents/MacOS/grass.sh'; exit
Rebuilding Addon HTML manual pages index...
Rebuilding Addon menu...
dyld: DYLD_ environment variables being ignored because main executable (/usr/bin/osascript) is code signed with entitlements
Python 2.6.7 found.
Cleaning up temporary files ...
Starting GRASS ...

Chunk 2: from selecting a location/mapset in the GUI startup window and clicking "Start GRASS".

          __________  ___   __________    _______________
         / ____/ __ \/   | / ___/ ___/   / ____/  _/ ___/
        / / __/ /_/ / /| | \__ \\_  \   / / __ / / \__ \ 
       / /_/ / _, _/ ___ |___/ /__/ /  / /_/ // / ___/ / 
       \____/_/ |_/_/  |_/____/____/   \____/___//____/  

Welcome to GRASS 6.4.2 (2012) 
GRASS homepage:                          http://grass.osgeo.org/
This version running thru:               shell (/bin/zsh)
Help is available with the command:      g.manual -i

See the licence terms with:              g.version -c
If required, restart the GUI with:       g.gui wxpython
When ready to quit enter:                exit

gregory@Gregorys-MacBook> Mar 23 11:31:05 Gregorys-MacBook.local pythonw2.6[2520] : CGContextRestoreGState: invalid context 0x0
Mar 23 11:31:05 Gregorys-MacBook.local pythonw2.6[2520] : CGContextRestoreGState: invalid context 0x0
Mar 23 11:31:05 Gregorys-MacBook.local pythonw2.6[2520] : CGContextRestoreGState: invalid context 0x0
Mar 23 11:31:05 Gregorys-MacBook.local pythonw2.6[2520] : CGContextRestoreGState: invalid context 0x0
Mar 23 11:31:05 Gregorys-MacBook.local pythonw2.6[2520] : CGContextRestoreGState: invalid context 0x0