That's what you're seeing at the 30 minute mark.
On the Control Panel of my computer the 'Power Schema' in 'Power Options' is set to 'Always ON' with the "Turn off Monitor" option set to 'After 2 Hours.' All other options are set to 'Never.' 'When press the power button' set to 'Shut Down', 'When press the sleep button' set to 'Hybernate.' The Hybernation is enabled.
But always exactly after 30 min without input from the keyboard or mouse the screen gets black with MS Windows Logo dancing on it. The PC continues to work. Any input makes the startup screen to appear. After click on the appropriate user icon the screen restores to the mode it was before the blackout.
I would like do not see this black screen before 2 hours witout input.
I run the HP Pavilion a320n withWindows XP Home SP3.