Orders with total null in checkout - could it be caused by this module?

Hi all,

I described an issue here (http://drupal.org/node/1902790) with orders in checkout which have a total of "0.00" - I use this module in conjunction with a product which is always in this orders... but I just have two products and this one is the product which is ordered mostly so it may not have anything to do with my issue. I just wanted to ask if someone of you guys had had a similar problem.

Best,
Tobias