samba - Oct 2007 - Samba 3.0.26a on RHEL 4U5 and "No network interfaces found"

Hi all,
 
yesterday I upgraded one of my RHEL 4U5 servers to Samba 3.0.26a and after that
I got a lot of warnings in the logs about "No network interfaces
found".  The server was
running fine in the past with Samba 3.0.24.
 
I tried to compile the "interfaces" program from
source/lib/interfaces.c and found out that
I don't get any list of interfaces neither with version 3.0.24 nor with
3.0.26a.
 
Any idea what's wrong here?
 
Thanks a lot,
christian