I'm using a ATI Radeon HD 4850 GDDR3 PCI-E HDMI graphics card on my windows 7 desktop with a Hanns-G HH251 monitor.
While using my computer, the screen will cut off stating that there is no input recognized and my computer sounds different once it happens. I've tried to update the drivers, however, it won't allow me to because once I start the installation process, it cuts off. I've used other graphics cards and they work fine. Pretty much, if I'm surfing the internet, watching a movie, playing music through my ZUNE software, or playing a game, the problem occurs. I can boot it up and it will do it every now and again. If there is sound playing through my speakers, it distorts as well. The computer doesn't shut off at all, the screen just disappears.
I would say your video card is the problem. Check and remove any dust from the heatsink. Try video card in another computer and test monitor on another computer also.
What power supply are you running?
What I don't understand is that everything that is in my computer is exactly in another computer that my roommate has. The only thing that we have different is our monitors. But when i get the chance to check it in another computer i will.
Thanks for the feedback. I can't remember what all is in my computer because my roommate helped me put it together because I don't have the computer knowledge to do so haha.