I came across the same problem on a combined wp/bbpress setup.
twas a simple case of changing line 1079, template-functions.php
$r = bb_get_option('uri') . "profile/" . $user->$column . ( 1 < $page ? "/page/$page" : '' ); to $r = bb_get_option('uri') . "profile/" . urlencode($user->$column) . ( 1 < $page ? "/page/$page" : '' );
