on win xp I have 4 vertical yellow lines on my screen. lines are there even when a program is running.

grumpyhugs, I can absolutely assure you that the yellow lines are not a 'feature' of Windows XP!

Without further information, it's impossible to tell you anything more useful. It would help for you to let us know some of the 'specifications' of your system - Motherboard ID, display card, and so on.

Dude take a screen shot unless it's your monitor press PrintScrn button or PrintScreen. Then paste it in like paint or photoshop or some kind of picture editing tool save the picture and post it.

Actually this sounds like what is happening to me.... and usually when I scroll up and down it gets worse.
I have swapped monitors and video cables but the problem stays there...
I have tried using the onboard VGA drivers rather than my radeon but the problem is still there...
Oh, and the problem gets worse then better...
I have included a doc with a screenshot of a word doc that shows the problem.. notice how the lines don't extend past the bottom of the document to the window frame ?
But then when its bad I get bright spots of pixels over the screen that come and go..
Any ideas ?

Your problem is exactly the same as the problem I am having. Have you discovered what the answere is? If you have I would be very interested to know.

By the way I have a Radeon 9800xt video card - could it be a problem with the card? The yellow lines first appeared after my system crashed.

yikes, your hardware is going bad! its either the video card or mbo