Hi Barry,
thank you for your reply… here is my code: http://pastebin.com/fqanAnyb
This code is from my functions.php, and I call rm_related_posts(get_the_ID()); in my single-post.php.
Uncommenting line 21-22-23, I can see that somehow WP_Query has been modified adding ‘tribe_events’ to the ‘post_type’ parameter.
DV