afni.nimh.nih.gov

Check which version of XQuartz you are running (from the "About XQuartz" menu item on the Mac menu bar item for "XQuartz"). Here's a message from AFNI that might be relevant (or might not be):

++ If you are using XQuartz 2.7.10 (or later), and
 + AFNI crashes when opening windows, you might need
 + to set an environment variable to solve this problem:
 +   setenv DYLD_LIBRARY_PATH /opt/X11/lib/flat_namespace