Sometimes it is very frustrating to get error 324. The server just says there is no data and the server has closed connection, which seems very mysterious and capricious. Unluckily, for the moment there is no direct evidence could indicate what the real problem is and here are some potential reasons that may be accountable: 

1. Google Chrome

Sometimes this problem only occurs in the Google Chrome which means the website may work well in other web browsers like IE, FF instead. 

2. PHP APC

Although people may not definitely confirm that the compatibility issue caused by APC between hardware and software can be the potential issue. So sometimes change the value of configuration in the apc.ini might help. 

apc.include_once_override=0 

Also check

• Error 324 (net::ERR_EMPTY_RESPONSE): Unknown error. and DRUPAL
• http://drupal.org/node/807680#comment-3134594