Once in a while, I'd say one time out of every 10 or so, when PHP is transparently adding the session ID to links, it causes apache to segfault.

The page only displays half way, and then looking at apache's error_log, it says:
[Date][notice] chipd pid 111 exit signal Segmentation fault (11)

PHP was compiled with the options: 
--without-mysql --with-apxs=/usr/local/apache/bin/apxs --enable-trans-sid --with-custom-odbc=/opt/SYBSasa6

php.ini is the stock "php.ini-optimized" with these options changed:
session.name = OPSESSID
register_globals = On
include_path = /usr/local/apache/htdocs/include

Like I said, it only does this maybe one out of every 10 page loads, and always at seemingly random places (I can't re-create the circumstances that cause it).