"turn off display" option in ctrl panel power options

you know how you can set the computers display to shut off after a certain amount of time via the power options menu in control panel? well maybe I am nuts but when I used to set this option, the display would actually TURN OFF. Now it appears to be turned off but it is not, it is just a black screen, but I can tell it is still ON.

The only thing I can think of is I updated to the latest bios A06 like a week ago, but I only noticed this yesterday. (although I could have missed it)

what can cause this? is anyone else experiencing this subtle but annoying issue?

oh yeah..I have a studio 1535 laptop with windows vista SP1

thanks in advance for any suggesstions!