Vista won't sleep when on AC power and screensaver on - gpzb

I have Vista Home Premium.  If I have the screen saver set to come on, the
computer won't enter sleep state if attached to AC power.  However, it works
fine on battery.

I don't have any wireless devices attached.
I already changed it to allow to sleep in multimedia settings.

It works fine when I set screen saver to none.  I can do this but it is a
bit annoying.

Any ideas?
Thanks !