It will sleep if I go thru the Apple menu and select 'Sleep'.
In the Energy Saver panel, I have it set for the computer to sleep after 2 hours of inactivity; the monitor slider is greyed out (I didn't check the box). Check box for the hard drives is not checked.
When I come back after 2 hours, the monitor is sleeping but the computer is running as normal. Move the mouse, monitor wakes up. Computer running as normal.
Anyone?