We have a MAS Server doing our Voicemail. It seems like 2-3 times a week our MAS is Shutdown when I arrive at work. Although Being on at 7PM when I leave.

It is in a Locked Rack in a severroom with Little to No access except myself and 1 other person. Any Ideas on what could be causing it to shut down durring the night.

It is on a UPS along will all other Servers in that rack. The event Log shows nothing out of the ordinary.

Is your server room cool enough? If not and the MAS gets to a specific temp it will shut down automatically to prevent damage to itself.

Other than that, have you called tech support?