I hope this problem is not only Irix specific.
The nis-lookup for an entry in auto.home-map has a trailing newline. This was stripped in samba releases before 3.0.2x.
Starting with samba 3.0.20 this behavior changed to NOT stripping the trailing newline after the nis-lookup. So I tracked the problem to the automoun_lookup function in source/lib/util.c.

In samba-3.0.14a the function automount_lookup (source/lib/util.c - NOT nisplus) the end of the string is marked with '\0'. This leads to the correct result.

-- 3.0.14a

strncpy(last_value, nis_result, nis_result_len);
last_value[nis_result_len] = '\0';
strip_mount_options(&last_value);

-- end

Starting with the 3.0.2x series the code changed to:

-- 3.0.2x

fstrcpy(last_key, user_name);
pstrcpy(last_value, nis_result);
strip_mount_options(&last_value);

-- end

Unfortunatly the trailing newline from the nis-lookup was no longer stripped.
The log results in:

[2006/03/31 08:54:51, 0] smbd/service.c:(660)
  '/usr2/people/hertha_' does not exist or permission denied when connecting to [hertha] Error was No such file or directory

-- log.

The real result should be /usr2/people/hertha, so the newline changes to underscore.

Solution:
Changing the code to:

fstrcpy(last_key, user_name);
pstrcpy(last_value, nis_result);

--> last_value[nis_result_len] = '\0';

strip_mount_options(&last_value);

-- end.

The result will be correct an the connection is successful.

I don't know if this is a patch or more a hack ;-). I found no trim function, that would the correct solution.

--maik.hertha./