VMware restarts every day.

I'm running VMware ESXi, 4.1.0

It's been restarting every day at exactly 4:09 PM

I have 3 virtual servers that get rebooted at 4:09 PM because of this and in the system logs it always says 'Unexpected Shutdown'

Is there a setting I need to look for? The events only go back to 4:17 PM after everything comes back up.

I have looked at every setting I can find and I'm getting no where.