Even I am facing the same issue in one of my shared server. I tried to look the same in the log. But I am receiving the following error.
# tail -f /usr/local/cpanel/logs/safeapacherestart_log
[2012-06-04 17:10:37 +0800] info [safeapacherestart] Apache httpd is disabled, cannot be restarted
[2012-06-04 17:28:23 +0800] info [safeapacherestart] Apache httpd is disabled, cannot be restarted
Apache is disabled via /etc/apachedisable. I am not sure how to fix it. or how to disable apache via cPanel. Can you please elaborate?