Monitor will not sleep after NIS 2011 upgrade

Recently downloaded NIS 2011 free upgrade. Ever since my monitor will not go into sleep (power save) mode. The screen saver works normally but not sleep mode. Seems that something in Norton is keeping it awake. Tried turning off optimizer but no change. Did not have this problem with NIS 2010. No other software/hardware has been recently installed. Windows XP SP3.