SQL error when first entering Forums + template.php problem

Stats:
Drupal 5.7
MySQL database 4.0.27
PHP 4.4.2
PHP register globals Disabled
Unicode library PHP Mbstring Extension
Web server Apache/1.3.36 (Unix) mod_auth_passthrough/1.8 mod_log_bytes/1.2 mod_bwlimited/1.4 PHP/4.4.2 FrontPage/5.0.2.2635.SR1.2 mod_ssl/2.8.27 OpenSSL/0.9.7a

I installed Advforum and followed instructions (to the letter is it thought...)
advforum theme files are in sub-folder off bluemarine
advforum module is under /sites/all/modules

Created template.php for bluemarine theme using code guide for just the advanced_forum option. Noticed that http://drupal.org/node/207841 says do not use ?php tags.
This caused the code to appear at the top of my pages so I added the tags and the code disappeared.

But when first going into Forums from the main menu I get the error message :

user warning: You have an error in your SQL syntax. Check the manual that corresponds to your MySQL server version for the right syntax to use near 'SELECT title, created AS time, query: SELECT n.title AS topictitle, r.title AS replytitle, r.time timestamp, r.type AS replytype, n.type AS topictype, n.nid AS topicid, t.tid, r.cid AS cid, r.uid, u.name FROM node AS n INNER JOIN ( (SELECT title, created AS time, nid, uid, type, 'cid' AS cid FROM node ) UNION (SELECT subject, timestamp, nid, uid, 'comment', cid FROM comments WHERE comments.status = 0 ) ORDER BY time DESC ) A in /home/lroca/public_html/includes/database.mysql.inc on line 172.

Further, even with the template.php file in place the actual forum posts remain in old Drupal forum style.
Is this connected with the SQL error above?

The code in my template.php (Bluemarine had none before) is

  if (module_exists('advanced_forum')) {
    $vars = advanced_forum_addvars($hook, $vars);
  }

I am not sure how to actually check that I am not returning array() at the end.

Any guidance appreciated.
The style of Advance Forums is great by the way - a good improvement on the standard - thank you for your effort!