Hi, some more experiments led to a possible solution of the problem, but I am not sure that this should be the final word. If I set the macro BOOST_NO_INTRINSIC_INT64_T, e.g. by giving CXXFLAGS=-DBOOST_NO_INTRINSIC_INT64_T when configuring the compilation process or as to-DBOOST_NO_INTRINSIC_INT64_T gcc on the command line, the problems disappear. This macro should be set in boost/serialization/collection_traits.hpp. It seems that the respective information is not correctly extracted under the conditions when I find the failure: boost 135.0 (RC2) gcc 4.3.0 x86_64 I do not understand the serialization code enough to make a suggestion about how to resolve the underlying reasons for this, but I hope that some expert could fix this. Best regards Bernd