Not a bug, but an inconvenient default.
By default samba searches for the user's base under "ldap suffix". But this
limits samba objects and users's objects to be under the same subtree. For
example, you cannot use ou=Samba,dc=my-domain,dc=org as "ldap suffix" and have
users "ldap user suffix" under ou=Unix,dc=mydomain,dc=org. It would be more
reasonable if users's and computer's lookups were done under the same suffix
they're added. It's not always that is possible to mix samba and Unix objects,
especially when you have a large directory service.
fixed in 3.0.11
sorry for the same, cleaning up the database to prevent unecessary reopens of bugs.