I have installed vb classifieds to take a look at its functionality but when I try to run dbtclassifieds.php the url jumps to my old /classified/ forum. I am running DB SEO so perhaps I change something in there?
This is not a bug, you'll either need to disable the DBSEO rewrite rules for Classifieds, change the forum rewrite rules to include the forum ID, and/or rename the old forum.