Hey,
Where do you check that? I've been having similar issues with some of the assets on my website (like css or the occasional image) not being served because of a 508 response... Which is actually ridiculous considering it's doing absolutely nothing other than some tests I've made with codeigniter, session, simple reading from a db and display a couple of pages of an html template! And I've been looking everywhere on my cPanel for feedback (on CPU or RAM usage) on what might be happening, but without success!