I keep getting "Error 21: selected disk does not exist" when I try to boot as WindowsXP
and then it says push any key to continue...and I'm returned to initial grub boot-up page (where I choose which OS I want to run). Intuition tells me that this problem is some sort of newbie-like error that I'm overlooking...
Your ubuntu installer was smart enough to try the map/map trick, but it does not always work. The problem is Windows throws a fit if it is not on the first physical drive in the system.
Back up your menu.lst, and try these changes to the Windows entry:
title Microsoft Windows XP Professional
map (hd0) (hd1)
map (hd1) (hd0)
Have a look at the manual if you want to read more on this problem: http://www.gnu.org/software/grub/man...2fWindows.html