How often does that happen? You sure the comp hasn't crashed? I had that happen to my comp a long time ago and it wasn't my monitor, but was cause my comp had crashed and hard locked on me while I was away. That happened to me due to an unstable vid card at the time.
Computer is fine, happens alot. My 2 year old touches something and when i come back in room monitor is in power save and this time a cant seem to get it out.l
OK fixed it. I turned off the computer, unplugged the power supply, swtiched the power supply off. Waited a few minutes, plugged everything back in and it worked.