Screensaver settings aren't used after startup

[Ralf Mardorf]

Hi :)

if I disable the screensaver for Xfce4 or wish to start it in 240
minutes, instead of the 10 minutes default, by xfce4-settings-manager >
Screensaver, it only works for the current session. After a new startup
the new settings are ignored. For the GUI the settings will be kept at
"disabled" or "240 minutes", but I get a black screen after some
minutes.
Unfortunately the screensaver is active, if I watch videos.

At the moment "Blank" and "Cycle After" are set to 240 minutes, display
power management is disabled for my Ubuntu Studio 12.04 LTS (Precise)
x86_64, this is the output of
$ xset -q
[snip]
Screen Saver:
  prefer blanking:  yes    allow exposures:  yes
  timeout:  0    cycle:  0
Colors:
  default colormap:  0x20    BlackPixel:  0    WhitePixel:  16777215
Font Path:
  /usr/share/fonts/X11/misc,/usr/share/fonts/X11/Type1,built-ins
DPMS (Energy Star):
  Standby: 7200    Suspend: 7200    Off: 14400
  DPMS is Disabled

For "Application Autostart" the "Xfce Settings Helper" was disabled. I
enabled it right now, but can't reboot yet. Even if this should do the
trick, I wonder why the screen gets black after some minutes, when the
settings are "disabled" or "240 minutes".

Regards,
Ralf