Apache随机失去查看文件的权限

我有一台运行Apache和MySQL的服务器(Leopard Server,不是我的选择)。几个月前,服务器开始随机发出“禁止”错误,从而阻止了对PHP应用程序的访问。这种行为随机地停止了。

Now, several days ago I installed Passenger and deployed a Sintra/Rack application. The application runs as a user acarneg (for example) from /Library/WebServer/Documents/presto/current/public, acarneg owns the entire structure. The _www user has access to the directory via ACL chmod +a "_www allow read,write,...".

Everything works great! But after a randomish interval, often ~12 or ~24 hours, Passenger throws an error that also prevents the PHP application from running. Passenger Error #2. Cannot stat file config.ru. Permission denied. But the permissions haven't changed (confirmed) and all one has to do to resolve the error is sudo apachectl graceful.

如果权限没有更改,并且Apache似乎没有合法问题,那么是什么原因引起的呢?为什么它之前停止了,为什么又恢复了!?!?!?

谢谢您的帮助!