Hello, I have had a mac pro from early 2008 and it worked properly until about 6 months ago. After a few hours of use the screen will randomly turn black while active. Most of the times it will black out when I leave the room for 5-10 minutes. The computer is completely unresponsive and I have to turn it off and back on for it to work again. In fact, while I was typing this the first time my screen blacked out and I had to re-type this whole thing. It is extremely frustrating and I'm sick of this problem. It isn't a screen saver setting and the cords are plugged in all the way. Also, the Mac has plenty of breathing room so it isn't overheating. I have looked everywhere for similar problems but it seems like I'm the only one! Any help at all would be greatly appreciated. Thanks!