Intermittent apache crashes and WSOD

Our Apache server has intermittent crashes. Sometimes 500's but also Intermittent "White Screen of Death" and a consistent WSOD everytime Apache is restarted. We can ssh "service httpd restart" to get things back. To get around the WSOD after restart we "wget". Nothing is showing up in the error logs that point at anything specific.
We are running WPMU.