Okay, I have been busy reading all these posts, but it seems there is a load of potential problems.

I just bought a new lcd monitor (a Viewsonic VA721), my computer is about 4 years old, an HP 512n. Got everything connected and working okay, but the monitor goes black after being on for some time...maybe half an hour. Someone suggested playing music in the background to help diagnose...when the screen goes black, music also stops, so not a monitor problem? Also I noticed that the hard drive light goes out, too.

Hopefully, this is enough information to get me closer to the actual problem. Thanks in advance for your help! :cheesy:

Could you check over your Power Options (in the conrtol panel).
See if your PC is set to go to Hibernate or Stand By after a certain amount of time. If it is, that is the likely cause.

Thanks, David. No it is not set to hibernate..I never had this problem until getting the new monitor and I have not changed any settings. Once it goes black, the only thing I can do is reboot again, then it is good for another bit of time. From what I have been reading it seems it could be the video card, motherboard, BIOS...I am hoping that someone can help me deduce what is the most likely problem. Thank you!