Unable to boot Windows partition using ntldr

[james]

Hello list!

I'm encountering an issue with GRUB 2.02.beta2-5 in which I can't seem 
to chain load a windows partition on my USB stick

The relevant portion of my config is included below:

--grub.cfg

insmod part_msdos
set winpe3=(hd0,msdos6)

menuentry "Windows PE 3.1" {
  insmod ntldr
  insmod ntfs
  set root=${winpe3}

  ntldr /bootmgr
}

--end cfg

When booting my Windows PE installation from this configuration, I 
receive the error below:

--
File: \Boot\BCD
Status: [octal garbage]
Info: An error occurred while attempting to read the boot configuration 
data.
--

The error seems to obviously point to the boot configuration data as 
being corrupted or incorrect. However, when I bypass GRUB and boot 
directly from /dev/sda6, Windows PE boots completely normally, 
suggesting that not only is the BCD data completely fine, but even the 
PBR seems to be working properly. I have also tried chainloading using 
the following configuration

--grub.cfg

insmod part_msdos
set winpe3=(hd0,msdos6)

menuentry "Windows PE 3.1" {
  insmod chain
  insmod ntfs
  set root=${winpe3}

  chainloader +1
}

--end cfg

This configuration doesn't even get me as far as the bootmgr error. 
Instead, I just get the less than descriptive message, "Boot error".

Everything I have seen gives me more than ample reason to believe the 
boot data on this partition is completely valid. That leaves me with the 
conclusion that I have somehow misconfigured GRUB. Does anyone have any 
pointers for additional troubleshooting? Any suggestions or help greatly 
appreciated! Thanks in advance!

--
James Lott