auth/auth_util.c:make_server_info_sam(840)
  User nobody in passdb, but getpwnam() fails!

I never found the solution to this in the web, as usual so I thought I'd post the fix.  In plain English smbd is telling us that the user "nobody" does not exist in /etc/passwd.

You can simply add this to your /etc/passwd file like so:

nobody:x:65534:65534:nobody:/nonexistent:/sbin/nologin

Now SAMBA/smbd should start fine and you won't receive anymore errors.