php segement fault in php5.5 that randomly appeared in certain forked processes ... in the end it was an issues with the package and the kernel. Still as soon as you have to use the strace + gdb with php you know there is a bigger issue :)
you should've seen my bosses face when he came to check what I was doing ... well all of the sudden a system upgrade moved up in the priority list of the company ;D .... it actually was about curl requests for our "automated installation process" so basically some of our customers did get wordpress/drupal installed others well ... lets just say ;D the system didn't stop trying ;D .... and sometimes they got lucky ^^