PHP5, amd64, phpdocumentor, squirrelmail

I've been having many troubles with PHP since i moved to a 64 bit server a couple years ago. Most of these problems are related to recursion, references and sockets and usually do segfault. My idea is that the stack is filling up much quicker on this architecture. Anyway, back to the specific problem. PHPDocumentor 1.3.0RC3 behaves like this on my amd64 gentoo box: PHP 5.0.4: works fine PHP 5.0.5: segfaults PHP 5.1.0: eats up all available ram This is squirrelmail 1.4.4 PHP 5.0.4: works fine PHP 5.0.5: segfaults on reply and forward Tried different kernel versions and upgraded most libraries and various php dependencies many times in months. ./configure with almost same parameters for all versions. Anyone else with similar problems? Thanks