[Soekris] net4501 with ff:ff:ff:ff:ff:ff MAC address

[b.candler@pobox.com]

One of the net4501's we received was refusing to PXE boot. It had bios 1.24 
so we updated it to bios 1.32 using XMODEM. 

It now gets as far as sending a DHCP request, but fails to get an ARP 
response. It turns out this is because it thinks its own MAC address is 
FF:FF:FF:FF:FF:FF. 

The only reference I could find to this problem was 
http://lists.soekris.com/pipermail/soekris-tech/2005-August/008968.html 
which suggests that the EEPROM is uninitialised, and that if I fiddle about 
to make a bootable CF card containing natsemi-diag, I might be able to write 
a MAC address into it. 

My questions are:
(1) could having other uninitialised EEPROM areas cause me problems? Should 
the unit go back to the supplier anyway for safety?
(2) is there a way to determine what the MAC address of the unit should have 
been, or do I end up picking one at random? 

Thanks, 

Brian.