The computer boots to WIN XP Home, sometimes, but then the screen is covered in pixellated boxes so it is impossible to do any sort of visual test. Cannot even get to ‘Safe Mode’
The fact that the first display gets to windows suggest that video card must be alright but within 2/3 seconds it has gone haywire, this suggests it IS the video card, I think.
When it hasn’t got to windows the creen is blocked with large squarish monotone blocks with traces of, well, colour (Sorry, I’m English!)
If the screen is obscured by the maze that developes, then I cannot see to download anything!
I am writing this on another computer that has no CD writer so cannot utilise this, but even then the problem would be to command the the faulty computer because I can ’see’ nothing

Try removing the card then boot up if this runs windows with on board graphix install the drivers for the video card or download the latest drivers from the cards maker http://www.nvidia.com/content/drivers/drivers.asp if its nvidia that is also check that the pc to monitor cables are secure i had this problem just 4 days ago i installed new drivers from nvidia everything is sweet (touches wood) good luck and i know how annoying this is