I'm using the March 2005 CTP beta of VS2005, and building for AMD64. I'm getting these errors with filesystem (fresh from CVS): boost\config\abi_prefix.hpp(19) : error C2220: warning treated as error - no 'object' file generated boost\config\abi_prefix.hpp(19) : warning C4103: 'boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\filesystem\path.hpp(20) : warning C4103: 'boost\filesystem\path.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\config\abi_suffix.hpp(20) : warning C4103: 'boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\filesystem\path.hpp(170) : warning C4103: 'boost\filesystem\path.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\config\abi_prefix.hpp(19) : warning C4103: 'boost\config\abi_prefix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\filesystem\fstream.hpp(21) : warning C4103: 'boost\filesystem\fstream.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\config\abi_suffix.hpp(20) : warning C4103: 'boost\config\abi_suffix.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) boost\filesystem\fstream.hpp(190) : warning C4103: 'boost\filesystem\fstream.hpp' : alignment changed after including header, may be due to missing #pragma pack(pop) -- Cory Nelson http://www.int64.org