PHP segfault on admin/content/types/CTYPE/fields

'Ere's an odd one. Using PHP 4.3.3 on Apache 1.3.28, with CCK 1.1. If I hit admin/content/types/fields, everything shows fine. If I hit admin/content/types/CTYPE/fields, however, my PHP actually ends up segfaulting:

[4185] PHP crashed on opline 82 of usort() at /srv/www/htdocs-v5/modules/menu/menu.module:755
[Sat Jan 13 09:50:53 2007] [notice] child pid 4185 exit signal Segmentation fault (11)

If I modify content.module and comment out:

  'callback arguments' => array('content_admin_field_overview_form', $content_type['type']),

I don't get the segfault anymore (but, of course, I get error messages from Drupal/CCK).

Still investigating.