I'm getting vertical lines on my Windows XP PC's screen. This is an example of it at its worst:
This all started the first time I turned the PC on after a windows update a few days ago. It updated Silverlight, and there were 2 updates to Visual C++. I shut down my PC after starting the updates, but as usual my system simply said it was completing the update first. I have done this before and never had a problem. I checked after these problems began, and only the Silverlight update was in my update history.
Now, these lines are not there all the time. Sometimes they appear before the windows log in screen or on the windows xp loading screen, sometimes not. They also appear in safe mode with my video card completely uninstalled (though still physically inside). Sometimes they are not as bad as that screenshot, and if I minimize the window or even scroll down and up again, they disappear. They appear at random, it seems to make no difference if I'm watching video or browsing, they even appeared after the system had been idle for an hour. Sometimes they flash or change colour.
So far, I've uninstalled my video card, uninstalled everything ATI related, used driver sweeper in safe mode to get anything that missed, and installed the latest drivers from scratch. Every time I do this, it seems to fix the problem, but after a while I get a few lines that appear and disappear at random, but the next time I shut down, when I turn it back on, it's really bad like the 1st screen shot.
I've also uninstalled Silverlight and the Windows updates that I was doing before this started happening, and reinstalled Silverlight.
The system is quite old, the card is a Radeon Pro 9800, and I'm leaning towards the card just being about to die, but the way it's so inconsistent, and that re-installing the drivers (and that it even happens without the card installed) makes it go away for a while, has me wondering if it's something driver or software related instead, so any ideas are welcome.
May also sound silly but it could be as simple as a bad monitor cable. Try another monitor or cable if you can. See if wiggling the card or cable changes anything when the problem is happening.
I used to own one of the ATI 9800 Pro cards, like yours. I believe they made an early PCIE version of it that didn't pick up too well, as most of them are AGP cards. If it's AGP, I'm going to go with heat damage or loose/faulty AGP slot connections. It's hard to determine since your issue is randomly occurring.
[EDIT] I forgot to throw in a solution: As someone said above, the cabling/connection to the monitor could be a problem as well. So a different cable or a different video card (even a cheap PCI one) would help you narrow it down. But you said it does it even when the ATI drivers aren't installed, which is almost a guarantee that it's a hardware issue.