dark screen on new monitor (weird thing)

ok so I purchased a new 22 inch monitor and everything was working fine but im noticing that when I am watching videos after a short while and sometimes not at all the screen will just go completely dark, the monitor wont shut off and computer wont reboot. If I try to turn off the monitor and turn it back on I will see the LG logo as that is the brand for the monitor but then it will go dark again. Now I can leave windows on all day and it wont be like that unless im watching a video then it can be 10 or 40 mins before it does that. I can't press any keys or ctrl alt del to make it come back up. I checked the power settings and its set to never sleep or tun off display, I have made sure all the display drivers are updated properly this really baffles me.

I am running Vista with a Amd Quadcore phenom processor

Please any clues would help

 

Hmm... Initially I would think that there is a codec problem, but the video plays for some time. ... does this only happen when running the video full screen, or does it happen when running in a smaller window as well.

Is the video a DVD, MPEG, something you downloaded maybe? Youtube? Porn? What's the source?

If it is streaming online video it could be a multitude of things, your NIC might be failing when the incoming data packets are too massive. Video codecs might not be working correctly.

If it is a DVD, well, try a new player? ... Maybe a different application to play them?

Is it windows media player that is playing the files, VLC, quicktime?

I think we will all need some more information before diagnosing this for you

Best of Luck!