Diskless boot of Fedora: mount related error

I've been doing network (ie. PXE-based) installs of Linux for a while, and
I thought I'd take the next step of actually running a machine completely
diskless (mostly as an emergency boot mechanism). But I'm having an odd
problem.

I'm using Fedora Core 3 with 2.6.12-1.1381_FC3 because that happens to be
what's on my workstation. I've a DHCP and TFTP server up and working.
The PXE startup is getting the DHCP data, the initrd and kernel files are
being successfully retrieved, the init script in the initrd is running,
but the mounting of root is failing.

I built the initrd on my workstation with:

/sbin/mkinitrd -f --with=nfs --fstab=/mnt/1/etc/fstab initrd-2.6.12-1.1381_FC3_nfs.img 2.6.12-1.1381_FC3

where /mnt/1/etc/fstab contains:

192.168.2.108:/mnt/1 / nfs sync,hard,intr,rw,nolock,rsize=8192,wsize=8192 0 0
192.168.2.108:/usr /usr nfs sync,hard,intr,ro,nolock,rsize=8192,wsize=8192 0 0
none /dev/pts devpts gid=5,mode=620 0 0
none /dev/shm tmpfs defaults 0 0
none /proc proc defaults 0 0
none /sys sysfs defaults 0 0
none /tmp tmpfs defaults,size=1024m 0 0
/dev/hda /media/cdrom auto pamconsole,fscontext=system_ubject_r:removable_t ,ro,exec,noauto,managed 0 0

where 192.168.2.108 is my workstation. I've confirmed from another machine
that 192.168.2.108:/mnt/1 and 192.168.2.108:/usr are being properly exported.

The PXE file contains:

label main
kernel DisklessFedora3/vmlinuz-2.6.12-1.1381_FC3
append ksdevice=eth0 load_ramdisk=1 initrd=DisklessFedora3/initrd-2.6.12-1.1381_FC3_nfs.img network root=/dev/nfs nfsroot=192.168.2.108:/mnt/1 ip=dhcp


The error is occurring during the init script:

Mounting root filesystem
nfs warning: mount version newer than kernel
nfs_get_sb: invalid root filehandle
mount: error 22 mounting nfs
mount error 2 mounting none
Switching to new root
Switchroot: mount failed: 22
umount /initrd/dev failed: 2

and then the kernel panics.

I'm wondering if this is an NFS version problem, but this idea just
comes from a quick look at the code which can generate the "nfs warning"
and "nfs_get_sb" error. The command "rpcinfo -p 192.168.2.108" output includes:

100003 2 udp 2049 nfs
100003 3 udp 2049 nfs
100003 4 udp 2049 nfs
100003 2 tcp 2049 nfs
100003 3 tcp 2049 nfs
100003 4 tcp 2049 nfs

and I'm wondering if this is a problem that the nfsd on my workstation is
advertising v4. I'd try turning it off, but I don't know how.

Any ideas or suggestions or recommendations?

Thanks...

Andrew