Installing and upgrading help

for mysql 5 you might change the sentence of mod\forum\lib.php line 1305 in this way:

 return get_records_sql("SELECT $postdata, d.name, d.timemodified, d.usermodified, d.groupid,
                                   u.firstname, u.lastname, u.email, u.picture $umfields
                              FROM ({$CFG->prefix}forum_discussions d,
                                   {$CFG->prefix}forum_posts p,
                                   {$CFG->prefix}user u)
                                   $umtable
                             WHERE d.forum = '$forum'
                               AND p.discussion = d.id
                               AND p.parent = 0
                               AND p.userid = u.id $groupselect $userselect
                          ORDER BY $forumsort $limit");