problem with nfs install

[Greg MATTHEWS]

well... i'm stumped. has anyone successfully kickstarted redhat7.3 via nfs? 
i'm beginning to think there might be a problem with it. i'm using the vmlinuz 
and initrd.img from 7.3 (the files in images/bootnet.img and in 
images/pxeboot/ are identical). these are served up by tftp and if i edit my 
kickstart file to point to copies of the 7.1 cds then everything goes well 
(even with the 7.3 boot files) however if i change to point to 7.3 files i get 
this error:

VFS: Can't find ext2 filesystem on dev loop(7,0)

and the installation stalls before any partitioning of the disk. the nfs 
server reports that the mount request was authenticated and the nfs export can 
be mounted from installed nodes.

i just tried rewriting the ks file with close reference to the 7.3 
customisation manual but with exactly the same results. the fact that i can 
install 7.1 with this combination of vmlinuz and initrd.img suggests that the 
boot files are good and it *is* possible to mount an nfs from them. i've tried 
using a different machine to export the nfs but the result is the same, 
regardless that both shares are exported in exactly the same way.

i'll include the top part of the kickstart file in case anyone can throw some 
light on this, as well as my /etc/exports file.

tearing my hair out!

GREG

top of ks file ----->

auth --enablemd5 --enableshadow
bootloader --location=mbr
clearpart --all --initlabel
device eth eepro100
firewall --disabled
install
nfs --server 128.16.160.99 --dir /exports/7.3
keyboard uk
lan en_US
langsupport en_US
mouse --device psaux --emulthree genericps/2
network --bootproto dhcp
part /boot --size 50 --asprimary --fstype ext2
part / --size 512 --fstype ext3
part /usr --size 2048 --fstype ext3
part swap --size 1028 --fstype swap
part /var --size 1024 --fstype ext3
part /tmp --size 512 --fstype ext3
part /home --size 2048 --fstype ext3
reboot
rootpw --iscrypted <password removed>
skipx
text
timezone --utc Europe/London
zerombr yes
<----- 

/etc/exports on 128.16.160.99 ---->

/exports/7.3 128.16.160.0/24(ro)
<----