I will just check if this is a known issue here first. I upgraded from 2.6 to 3.3.1 and after that all sites reported http error 503, service unavailable. I downgraded to 2.6 again, but would like to upgrade later on if possible. Litespeed serves files other than .php just fine so it must be something with PHP and/or LSAPI? I built a new PHP as well, but that didn't help. As I'm down to 2.6 again I can't give much details, I will get the details you need if this is not a known issue.