Desktop black screen during using or opening of computer

Hello,

I am a ordinary computer user. Recently i faced some problems which i don't know how to do. I hope somebody can help me in solving this problem.

I am using Window 7 for my computer(desktop) now, Recently it become black screen while i am using it. Plus, sometimes i even can't start the window but i still see the computer got running. This only occurred in the certain time. When i don't open it for a few hours, it can run normally.

I had run a disk check, it shows no problem and had scan my computer, there is no bugs or malware on my computer. I even unplug and plug back my cable but it don't works.

Can somebody help me. Thanks a lot for those who try to help me.