Hi,
Beta goes offline for 15 minutes at around 2.45amCST Sunday morning for complete data backup.
Alpha backs up at 1.37am.
If you think Beta has crashed, go to
http://hostnexus.com/uptime2.php and check the monitor. If you see all thumbs down (except for DNS, I think) then it means the box is totally offline. This would never happen ordinarily and can only mean backup time.
If you see only httpd (Apache) with a thumbs down, then that means the web server has gone awry and needs restarting. (That's not a server reboot, just apache). You may see happen once a month or so. We monitor the network heavily 24/7 so can normally pick up on any problems before anyone else notices.