Prompted to shut computer down when turning monitors off?

[freaky]

I am running the latest version of Leopard on my MacPro and have dual cinema displays. Recently, a prompt started appearing that asks me if I want to shut down my computer and won't let me just turn off the monitors like I've done for years. I've looked through the options in System Preferences and can't find anything that is causing this.

Does anyone know what I need to do to be able to just turn off my monitors by pressing their power button?

[tagaiz]

If they are apple displays there should be a preference under displays that lets you choose what you want the power button to do. If not under displays its there somewhere.