I am able to load php 5.4 on my nginx server, but when I do, I get errors in the php log about the Zend Optimizer being the wrong version and since this is the only error I get, I suspect this is what is causing WordPress not to work properly.
WordPress works with:
Apache & PHP 5.2
Apache & PHP 5.3
Apache & PHP 5.4
Nginx & PHP 5.2
But it does not work with Nginx & PHP 5.3 or 5.4 while other PHP pages do.
So here are the lines from php.log:
Cannot load Zend Extension Manager - it was built with configuration 1.2.0, whereas running engine is API220100525,NTS
Zend Optimizer requires Zend Engine API version 220060519.
The Zend Engine API version 220100525 which is installed, is newer.
Contact Zend Technologies at http://www.zend.com/ for a later version of Zend Optimizer.