I was having the same runtime error problem, but I have XP pro on one drive and all of my computer programs on another.
When I installed reloaders guide to the drive and partition that contains XP, it worked fine.
I had about two other programs that would not run unless installed on the same drive and partition as XP.
It seems as though those programs are looking for something in the operating system and unless installed in the same, it can't find it and won't run.
Hope this helps.
Trent