mount: RPC: Authentication error; why = Failed (unspecified error)

Sorry for reposting this. I posted once but it never got onto the group,
as far as I could see.

After recent upgrades to my server, my DLW (
thin client will no longer boot.

Thin client: T1420, i386
Server: 64-bit AMD quad running Fedora 9
Linux Terminal Server Project (LTSP) version 5, installed using yum

The thin client seems to load all files by TFTP, but then I get the following messages:

Red Hat nash version 6.0.52 starting
mount: RPC: Authentication error; why = Failed (unspecified error)
nfsmount: error mounting on /sysroot as nfs: Bad file descriptor
/setuproot: moving /dev failed: No such file or directory

I interpret this to mean that the thin client is trying mount /opt/ltsp/i386
as /sysroot on the thin client. The IP of the server is correct.
As suggested in a posting about another RPC-related problem:

> /root#/usr/sbin/exportfs -v
> /opt/ltsp <world>(ro,async,wdelay,no_root_squash,no_subtree_check)


#/usr/sbin/showmount -a
All mount points on orpheus:

which is also what I expect to see.

I have tried rebooting the server, and even restarting rpcbind and nfs, with no luck.

/var/log/messages shows a bunch of DHCP messages that show that the thin client got
an IP address, and tftp started, which I already know because the thin client
got as far as downloading all of its files and booting up the kernel. Still,
the lack of error messages beyond that point is probably significant.

The above exhausts what little I know about NFS and RPC.

I have tried reinstalling
Hints on where to begin be appreciated.

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