I wasn't getting much help at the original forum so here is my post:

I'm working on a friend's computer (using it right now) . Here's a description of the problem:

When the computer is turned on, it will POST, display installed RAM etc. then when it would normally display a Windows XP progress bar/splash screen, the screen goes black and stays black until it is turned off manually. I can get into BIOS before the screen goes black to look through and edit settings, which I haven't changed. After looking through BIOS I can startup with safe mode only. System Restore is turned on so I tried to restore to an earlier date; this did not work. I can connect to the internet so I ran Trendmicro Housecall; this came up with zero malware, spyware, viruses, but found 49 microsoft updates. I tried to install these updates but came up with an error message, unable to install or something.

System specs:
Compaq Presario SR1834NX
Windows XP Media Center Edition

Any help is appreciated! Ask more questions if needed.

Dude I just had a problem like this. Try updating your drivers in safe mode until you find the right one. Mine turned out to be the video card.

got it. It turned out to be hardware. I started taking out all unneccessary hardware until it started up and it turned out to be the crappy little modem. problem solved!