When using session_unset on a page where no session variables have been set, session_unset causes the apache child process to segfault.  I'm using Apache 1.3.20 with PHP 4.0.6.  I've taken out the session_unset call and am just using session_destroy now, but I would think that session_unset should gracefully return even if there are no set session variables.  It seems to do this even on a page where I just set the session variables, and they haven't been saved yet. (IE, start a new session, register a session variable, then call session_unset all on the same page causes segfault).

My PHP configure looks like this:
./configure --with-apxs=/usr/local/apache/bin/apxs --with-openssl --enable-calendar --enable-ftp --with-gd --with-imap --with-kerberos --with-imap-ssl --with-ldap --with-mysql --with-pgsql --with-mm --enable-sockets --enable-sysvshm --enable-wddx

I'm using the MM session handler instead of files.