The gnome 2.28 has feature with poversaving that autosuspends machine after
certain amount of time to match up EU regulations.

This works fine but it is also enabled for GDM where it can be used as login
screen on servers. When your server suddenly suspends it is bit shocker, as
such I would recommend us to disable this behaviour for GDM and keep it only
for logged user sessions.

Workaround (not sure which of the two settings are used, i think the first):

su - gdm -s /bin/bash
export $(dbus-launch)
GSETTINGS_BACKEND=dconf gsettings set org.gnome.settings-daemon.plugins.power
sleep-inactive-ac-type 'nothing'
GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.session idle-delay 0