On my Debian Lenny server with Apache 2, PHP 5.2.6 and PostgreSQL 8.3.8, I get two errors when trying to access /fgallery.

* warning: pg_query() [function.pg-query]: Query failed: ERROR: invalid input syntax for integer: "" in /srv/www/htdocs/portal/includes/database.pgsql.inc on line 139.
* user warning: query: SELECT n.nid, n.type, n.language, n.uid, n.status, n.created, n.changed, n.comment, n.promote, n.moderate, n.sticky, n.tnid, n.translate, r.vid, r.uid AS revision_uid, r.title, r.body, r.teaser, r.log, r.timestamp AS revision_timestamp, r.format, u.name, u.picture, u.data FROM node n INNER JOIN users u ON u.uid = n.uid INNER JOIN node_revisions r ON r.vid = n.vid WHERE n.nid = '' in /srv/www/htdocs/portal/modules/node/node.module on line 749.

The patch is simple, change line 87 of modules/flash_gallery/flash_gallery.module from:
$galleries[$i]->latest = node_load(array('nid' => $last->nid));
to
$galleries[$i]->latest = node_load($last->nid);