Im just taking a shot in the dark, but there might be some variable that is different between xp and 2k that changes the amount of data or speed of data transfers across the network. With a piece of failing hardware I sometimes find that if you push it to 50% then it will run fine, but if you push it past that say to 75% it will crash every time. You might have been pushing it to hard with the xp machine since it might have been able to copy files across the network and higher speeds.....again im just guessing.
Andy