[boost] boost::filesystem changes since version 1.55.0

I have tried to upgrade our software from using boost 1.55.0 to 1.57.0. Now we're getting unexpected exceptions in our code using filesystem::recursive_directory_iterator. Checking http://www.boost.org/users/history/version_1_56_0.html or http://www.boost.org/users/history/version_1_57_0.html there are no changes concerning boost::filesystem. Is there somebody who can tell me what has been changed in boost::filesystem, versions 1.56 and 1.57, and what impact it has on existing code or what I have to adapt to fix our software? Regards, Armin Pies