"wavy" windows

When scrolling the screen goes wavy with little ripples in it. When I stop, the waviness stops. It's not the worst thing that has ever happened but I just wonder if there's a fix for this condition. I have Windows XP. I've just reformatted my hard drive and reinstalled windows xp. And I'm starting to load various programs.

You didn't reload your video drivers, probably amongst others. You need to go to the manufacturer's website and install the newest video drivers for your computer as well as for any other devices with a yellow exlamation point in device manager.

Thanks Apple. That was it. I went to Dell drivers and was able to input my service tag number and all the drivers for my computer were there. That's an excellent service Dell has. Never knew it before. They also have a place to check your drivers to establish whether they are working properly or not. And, last but not least, they have a written piece about which drivers to install in the correct order. That's neat. Thanks again.