Power Management Issue

[Guest Denver]

My computer is set to "always on" with turnoff the monitor after 15 minutes

of inactivity. Recently, I notice that after a hour of inactivity when I move

the mouse to turn the monitor back on there is a lot of hard drive activity

and it takes 3 to 4 minutes for the monitor to show a picture. However, when

I move the mouse the monitor green light does start flashing immediately. I

did a test and within 30 minutes of inactivity the monitor comes on

immediately with the move of the mouse. It only takes a long time when there

is no activity for at least an hour. What could be causing this behavior. Any

assistance is greatly appreciated.