Installing Windows 7 to iSCSI Target

[nry]

After lots of messing around I finally got my ESXi hosts all diskless booting with iPXE. Works perfectly

I am now trying to dual boot two of my ESXi hosts using a PHP script, which seems to work. But I can't quite get Windows 7 ultimate x64 to run the installer.

Using PXE to chainload iPXE, I can successfully get a DHCP request sent etc and chainload a mac address specific URL.

In the hosts mac file I have the following

Code:

#!ipxe

set keep-san 1
sanhook iscsi:10.0.5.10:::7:iqn.2013-05.server:n2win
chain http://10.0.5.10/win7/boot.ipxe

In boot.ipxe it's copied from the wimboot page
http://ipxe.org/wimboot

Code:

#!ipxe

kernel wimboot
initrd bootmgr          bootmgr
initrd boot/bcd         BCD
initrd boot/boot.sdi    boot.sdi
initrd sources/boot.wim boot.wim
imgstat
boot

If I boot without any san commands, the windows 7 installer loads no problem, but obviously finds no disks to install to.
As soon as I introduce the sanhook or sanboot command into my iPXE script the installer will load the black setup start screen "Windows is loading setup files"
After this I get a grey (or white) blank screen.

Once again I assume I am missing something blatantly obvious. Anyone got any ideas?