I am seeing this on my error_log:
[Tue Dec 16 02:47:55 2008] [error] [client nn.nn.nn.nn] mod_security: Access denied with code 500. Pattern match "^$" at HEADER [hostname "www.hostname.com"] [uri "/wp-cron.php?check=623219d0598131d782fa6c88192ca86c"]
Meaning that mod_security is bouncing these requests because the HEADER is empty. I can change mod_security by allowing self requests or not checking wp-cron.php requests but… is there any other way?