I am using the boost 1.33.1 distribution, and the xml_iarchive and xml_oachive to serialize a rather deep and complex data structure to xml. I am using make_nvp directly in all cases (not the macro). I am sometimes getting the following assert (line 71 in extended_type_info.cpp) when I load previously serialized data: assert( lookup(eti) == m_self->m_map.end() ); It seems obvious that what is happening is that somehow I am calling self_register more than once for a specific class. Tracing through the code however I am puzzled exactly how this could happen, since the registration should only happen once when the libraries are loaded. This never happens on save by the way, only on load. It also never happens if I do the save, followed by a load immediately. It only happens if I do the save, shut down the application, then load the data. I have verified that the loaded data is a bit by bit equivalent in both cases. The best that I can come up with is that I am loading the serialization library as a side effect of calling LoadLibrary at runtime. So I am linking in the serialization library after everything else has been loaded and is running. But again, none of the libraries are ever unloaded, and the load sequence should always be the same. The actual situation is that I have a library ... call it Library A, which is linked to libraries B, and C. The library A is being linked using the LoadLibrary call, each of libraries B are C are linked to the boost serialization library. In each of libraries B, and C, I have used the macro: BOOST_CLASS_EXPORT_GUID( class, "ClassNameText" ) To define all of my classes I am serializing, including all classes that I am serializing using shared_ptr's. I was thinking originally that the problems were all shared_ptr's of classes that are derived from enable_shared_from_this<T>, but I am no longer confident that has anything to do with it. In fact, truth be told, I have no idea if any of the above has anything to do with the problem. When I commented out the assertion, everything seems to work just fine, except now I am getting a stack overflow on very complex hierarchies in the spirit parser (again, load only), but the simpler ones seem to work repeatedly without any problems. I have no doubt that the assertion was added there for a reason, so I hate to comment it out without finding out what else I might have broken... Edward Reusser Principal Engineer Actel Corporation (650) 318-4972 The information contained in or attached to this email may be subject to the Export Administration Regulations (EAR), administered by the U.S. Department of Commerce, or the International Traffic in Arms Regulations (ITAR), administered by the U.S. Department of State, and may require an export license from the Commerce or State Department prior to its export. An export can include a release or disclosure to a foreign national inside or outside the United States. Include this notice with any reproduced portion of this information.