Originally posted by Rick
How big is your monitor? The message you are recieving is telling you that your monitor cannot support that resolution.
1600x1200 is out of range for most monitors 17" or less and some 19" monitors.
Theory: If you did not have your video drivers installed with Windows XP Home, then XP allows you to interlace the image at higher resolutions and supports full color with its VGA drivers although it is very slow. So it will show a 1600x1200 image on a 1024x768 monitor, for example.
Perhaps when you installed Windows XP Professional, it had the drivers for your video card and now you have video acceleration. It will no longer interlace a 1600x1200 image on a smaller monitor, but video acceleration is much, much faster and makes the whole computer feel much more responsive.
If this isn't the case, it may be worthwhile to update your drivers and perhaps your monitor INF drivers. You can download these from your manufacturer's website.