How to detect the conflict? - blocks not showing, menu-items do

Hi,

could someone give me an advice how to detect a conflict of TB with probably another module on a site?
The blocks aren´t showing up, while the menu-items do.

For troubleshooting I installed this custom theme + TB on a private site. There all works as expected.
So there must be a conflict with another module or function on that site.
I´ve got jquery-update version 1.7 (tried all others too).
No conflict in fire-bug console detected. But in the HTML-view the blocks are missing.
Normal menu items are displayed.

I´ve realized, that on the test site the TB menu stops working (the dropdown at all) when there is one of the superfish-menus is on that page in use, so there is very likely some conflict of this kind on the problematic site too (no superfish there in use).

Already disabled various modules that could be connected (menu_attributes, menu_blocks), no success.

Any hint someone how to detect this?

thanks

Vincent