Oh, I didn't know that you were using grub4dos to load the freeldr.sys as kernel.
If you already know the disk/partition (i.e. (hd0,0)), this is all you need in menu.lst:
title XP via ReactOS loader
root (hd0,0)
kernel /freeldr.sys
title XP via normal NTLDR
root (hd0,0)
chainloader /ntldr
What I was trying to tell you in my previous post is that you should not *need* grub4dos in this simple configuration.
You need:
1) the (hd0,0) partition (FAT32) with the normal XP bootsector invoking NTLDR
2) both the freeldr.sys (and freeldr.ini) and NTLDR (and boot.ini and ntedetect.com) on the (hd0,0)
3) a boot.ini *like* this:
[boot loader]
Timeout=20
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
C:\freeldrbs.dat="FREELDR"
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect
C:\grldr="Grub4dos"
(the third line invoking grub4dos is of course useful only if you have also grldr on (hd0,0))
4) a copy of the ReactOS FAT32 bootsector (of course with the correct partition data) saved as (say) freeldrbs.dat
I am not very familiar with ReactOS, let alone recent versions,
there might be needed an extra step for this to work[1]
In any case, you do NOT need (nor "want") to install grub4dos, a volume formatted under XP will load NTLDR and you can add the grldr entry (as in the example above) in BOOT.INI to load grub4dos without needing any tool to "install" it, actually you won't change anything in the normal disk as created from XP besides adding a few files.
Or, if you prefer, you can have the menu.lst with just the entry for freeldr.sys and a BOOT.INI *like*:
[boot loader]
Timeout=20
default=multi(0)disk(0)rdisk(0)partition(1)\WINDOWS
[operating systems]
multi(0)disk(0)rdisk(0)partition(1)\WINDOWS="Microsoft Windows XP Professional" /noexecute=optin /fastdetect
C:\grldr="Grub4dos that will load freeldr.sys"
Wonko
[1] unlike FAT12/16 the bootsector of FAT32 is not a single sector, but rather 3, in DOS/Win9x, these sectors are LBA 0,1 and 2 (the bootsector, FSINFO and rest of boot code), but 2K/XP put the third sector of the bootsector on 13th sector (sector at relative LBA 12) whilst ReactOS (at least older versions) puts it on 14th sector (sector at relative LBA 13), it has to be checked by comparing a "same" FAT32 partition formatted once by XP and once by ReactOS, very likely this 14th sector needs to be replicated on the XP formatted volume to have the bootsect mechanism work.