Screensaver problem

[JD]

Using Mate Desktop.
Ubunu 12.10 - latest updates as of a few hours ago.

$ ps -ef | grep -i screen
jd        3092     1  0 Apr22 ?        00:00:01 
/usr/bin/gnome-screensaver --no-daemon

So, it is not the Mate screensaver that is running.

$ ls -1 /usr/bin/*screensav*
/usr/bin/gnome-screensaver
/usr/bin/gnome-screensaver-command
/usr/bin/mate-screensaver
/usr/bin/mate-screensaver-command
/usr/bin/mate-screensaver-preferences
/usr/bin/xdg-screensaver

So why is the gnome-screensaver running
instead of the mate-screensaver ?

What conf file do I need to change to make the
mate-screensaver my screen saver?

In case you are wondering why I want to do this;
the current screen saver seems to not do it's job
after it works for a few times (i.e. after being interrupted by
keyboardor mouse eventsa few times, thenscreen stays lit
and does do it's job at all even if I leave the computer untouched
for all night. In the morning it is always lit. If I wake
up in the night and check, it is lit; i.e. display is full on.