monitor problems

hey, guys. ok, here's my problem. my monitor will just go off as if it's going to sleep. but it's not going to seep because it happens while i'm in the middle of using the mouse or typing something. and the power light doesn't go orange, it stays green. if i leave the monitor off for a while, like an hour or so then it'll be fine for like 30 minutes or so, but after that it starts going blank like this. and then i have to physically turn it off and then back on. then about every 5 to 30 seconds it'll go blank again. i tried doing a monitor self test by unplugging it from my comp and it said my monitor was working properly. can any of you guys explain what might be causing this?? thanks in advance to anyone who helps.

calibretto

 

If possible, try the monitor on a different computer. If it does not have the shut off problem on it, the next thing to look into is the video card/over heating problems with the computer itself.

 

I would try what Paul said but it sounds like the monitor is bad