[K12OSN] PXE boot stopped working after upgrade to 5.0

[Julius Szelagiewicz]

Dear Folks,
 I've upgraded an important production server in a very remote location to
v. 5.0. Everything seems fine, other than the fact that terminals no
longer perform PXE boot.
 What happens is that the dhcpd issues an address and points to a valid
boot file. Terminal than attemps to find this boot file in the
aproppriate directory. The search sequence that normally flashes too
quickly to read takes now over 15 minutes, ending with "Trying to load:
pxelinux.cfg/default", "Could not find kernel image: linux", "boot:"

I have copied over the /tftpboot/lts directory from a "known good" server,
already updated. No joy.
Please help - this is a production server, it is getting late ...
Thanks, julius