I have a sony vaio desktop, and I recently installed a new graphics card. Everything works wonderfully, the card isn't really the best, but it suites me fine. Just recently I found a huge problem, though. If I shut down my computer and leave it off for an extended period of time and turn it back on, it freezes at the windows xp screen, and the only way to get it to start correctly is to take the card out and then start it up and go through the process of reinstalling it, only to have it happen again if the computer is shut off for a while. Anyone have any suggestions? If so, thanks in advance.
Try downloading the latest version of Direct x - then the latest drivers for your video card.
Otherwise - the card may be too new for your computer (but I doubt it).
If you have Hibernate on, disable it.
Try finding the latest driver, it would also help if you tell us what Graphics Card exactly is it, I've had the problem before with a Radeon 9800 XT. I switched a Power Supply at it was fine.
Back to the point, without knowing exactly what Card/motherboard you have, it's kind of hard to help.
Could you give us some more details such as type of video card, which drivers your currenlty using and just in general the specifications of your computer. These things all help in troubleshooting. It's most likely a driver issue either with your motherboard or your video card.
Also make sure it's not overheating, new video card=more power so it might overheat. If that's the case then buy a new fan.
Not long ago I fixed a machine that had a similar problem. The person who build it forgot to hook up an extra power cable to the card. It required an IDE power connector to be connected to it for extra juice. But without more information from you it's really hard to tell.