Problema al convertir phpbb en smf

[etanol]

Hola foreros, se que hay gente experta en ambos foros (smf y phpbb) y que habeis conseguido con éxito la conversión de phpbb a smf.

Os comento: tengo en localhost los dos foros funcionando correctamente sobre una base de datos llamada "base_datos", el foro phpbb tiene la carpeta "foro" y el foro smf la carpeta "smf". (no tengo ningún usuario registrado en smf, solo el administrador)

Mi problema sucede al convertir phpbb en smf. He bajado el zip "smf_1-1-7_phpbb2_converter" y lo he descomprimido en la raiz de smf. Todo iba funcionando correctamente hasta el último paso en el que me tira este error:

Converting ranks... Successful.
Converting groups... Successful.
Converting members... Unsuccessful!

This query:
SELECT
u.user_id AS ID_MEMBER, SUBSTRING(u.username, 1, 80) AS memberName,
SUBSTRING(u.username, 1, 255) AS realName,
SUBSTRING(u.user_password, 1, 64) AS passwd, u.user_lastvisit AS lastLogin,
u.user_regdate AS dateRegistered,
SUBSTRING(u.user_from, 1, 255) AS location,
u.user_posts AS posts, IF(u.user_level = 1, 1, mg.ID_GROUP) AS ID_GROUP,
u.user_new_privmsg AS instantMessages,
SUBSTRING(u.user_email, 1, 255) AS emailAddress,
u.user_unread_privmsg AS unreadMessages,
SUBSTRING(u.user_msnm, 1, 255) AS MSN,
SUBSTRING(u.user_aim, 1, 16) AS AIM,
SUBSTRING(u.user_icq, 1, 255) AS ICQ,
SUBSTRING(u.user_yim, 1, 32) AS YIM,
SUBSTRING(u.user_website, 1, 255) AS websiteTitle,
SUBSTRING(u.user_website, 1, 255) AS websiteUrl,
u.user_allow_viewonline AS showOnline, u.user_timezone AS timeOffset,
IF(u.user_viewemail = 1, 0, 1) AS hideEmail, u.user_avatar AS avatar,
REPLACE(u.user_sig, '\n', '<br />') AS signature,
u.user_sig_bbcode_uid AS signature_uid, u.user_avatar_type,
u.user_notify_pm AS pm_email_notify, u.user_active AS is_activated,
'' AS lngfile, '' AS buddy_list, '' AS pm_ignore_list, '' AS messageLabels,
'' AS personalText, '' AS timeFormat, '' AS usertitle,
'' AS secretQuestion, '' AS secretAnswer, '' AS validation_code,
'' AS additionalGroups, '' AS smileySet, '' AS passwordSalt,
'' AS memberIP, '' AS memberIP2
FROM `base_datos`.phpbb_users AS u
LEFT JOIN `base_datos`.phpbb_ranks AS r ON (r.rank_id = u.user_rank AND r.rank_special = 1)
LEFT JOIN `base_datos`.smf_membergroups AS mg ON (mg.groupName = CONCAT('phpBB ', r.rank_title))
WHERE u.user_id != -1
GROUP BY u.user_id
LIMIT 0, 500;

Caused the error:

Illegal mix of collations (latin1_general_ci,IMPLICIT) and (latin1_swedish_ci,IMPLICIT) for operation '='

Mi pregunta es... ¿Cómo puedo resolverlo?

Gracias y un saludo.