I've had this problem previously with themes due to them timing out while loading the CSS. Switching on developer mode alleviated the problem due to the way the files load in that mode.
The real problem was that my max_execution_time setting in php.ini was way too low for my server. Bumping this time up fixed the problem.
The real problem was that my max_execution_time setting in php.ini was way too low for my server. Bumping this time up fixed the problem.