系统总是自动停止

有规律吗？看看apache的错误日志。

错误日志：
Thu Apr 14 12:57:43 2011] [error] [client 192.168.18.127] client denied by server configuration: C:/ZenTaoPMS/zentao/www/my-todo.html, referer: http://192.168.101.45:88/zentao/my-profile.html
[Thu Apr 14 12:57:44 2011] [error] [client 192.168.18.127] client denied by server configuration: C:/ZenTaoPMS/zentao/www/todo-create-20110414.html, referer: http://192.168.101.45:88/zentao/my-todo.html
[Thu Apr 14 13:02:44 2011] [error] [client 192.168.18.127] client denied by server configuration: C:/ZenTaoPMS/zentao/www/misc-ping.html, referer: http://192.168.101.45:88/zentao/todo-create-20110414.html
[Thu Apr 14 13:07:44 2011] [error] [client 192.168.18.127] client denied by server configuration: C:/ZenTaoPMS/zentao/www/misc-ping.html, referer: http://192.168.101.45:88/zentao/misc-ping.html
[Thu Apr 14 13:07:52 2011] [notice] Parent: Received shutdown signal -- Shutting down the server.
[Thu Apr 14 13:07:52 2011] [notice] Child 384: Exit event signaled. Child process is ending.
[Thu Apr 14 13:07:53 2011] [notice] Child 384: Released the start mutex
[Thu Apr 14 13:08:03 2011] [notice] Child 384: All worker threads have exited.
[Thu Apr 14 13:08:03 2011] [notice] Child 384: Child process is exiting
[Thu Apr 14 13:08:03 2011] [notice] Parent: Child process exited successfully.

看上去很正常，就是不知道从哪接收到了停止的信号。我们没有主动去关过。