I discoverd the following conflict with latest smf bridge 1.3.1.2 and the latest zoom gallery version.
When i try to use the lightbox function i get the following error message:

Fatal error: Unknown(): The script tried to execute a method or access a property of an incomplete object. Please ensure that the class definition <b>lightbox</b> of the object you are trying to operate on was loaded _before_ the session was started in /srv/www/[censored]/html/main/components/com_zoom/lightbox.php on line 59

After a long long time of searxching for the prob  i finally loacted the confilct in the index.php file which has been changed by the bridge. The following 2 code lines are obviously causing the problem:

if (file_exists($smf_path."/SSI.php"))
   require_once ($smf_path."/SSI.php");

After deleting those lines everything works fine.
Which effects could this have on the function of my smf and mambo? Do i really need them? And if yes is there another way to work around this prob?

if you want to check it on my side: http://www.scarabsam.de

Thanks for your help... I tried the new file but i still encounter the same issue. :-(
I'll continue trying with the deleted ssi commands.... seems as if that would be the only solution so far ;-)