3 months ago I installed a brand new Sapphire ATI Radeon HD 3650 and it has worked fine. This morning when I turned my PC on it showed the first 2 startup screens (the screens which allow "F" buttons to be used), the Windows XP screen with logo and a scrolling progress bar beaneath, then my monitor went blank. After about 5 seconds my monitor went into stand-by mode. Even though my monitor was blank, I could hear the tones that play when XP finishes and my Desktop comes up. I was able to get my display working properly again after switching the video back from PCI-E to my on-board chipset.
I've tried some simple troubleshooting I found in another thread here, and my Motherboard, RAM, and Power Supply are all fine. Some other comments on-line mentioned driver issues, so I downloaded and installed the latest driver released (10/15/08) from ATI, but when I tried restarting with the video switched back from on-board to PCI-E, I had the same problem. I could hear XP starting up fine, but my monitor went blank after the XP logo screen.
Due to my general computer-ignorance, I'm pretty much at the end of what I can find to try and diagnose the problem. Any help would be greatly appreciated.
If it's important, my PC is a HP Pavilion a1620n. My OS is XP Media Center '02.