Grub and network. Possible bug?

[antic 42]

It could also be me doing something silly, but I'm trying to configure
a computer to boot off the network. Ive created a menu item that runs
dhcp, root, kernel and module.
However, when trying to boot the item, I'm given
"error 1: filename must be an absolute pathname or blocklist"
this error comes from the dhcp step, and if I press enter, go back to
the menu, and boot that item again it works fine.

Now, I dont think its a problem with the dhcp server (if i go into
command line mode, type dhcp and hit tab it will give the same error,
without running the command) nor do i tihnk its a problem with the
network card (it can see the network card, and does get an ip address
from it)
Is there anything else I'm missing? All the documentation seems to say
that just running dhcp will make it work.

Thanks.