Got a whole mess of warnings when I moved some of my includes around, particularly this one: #include <boost/thread.hpp>

abi_prefix.hpp(19) : warning C4103: 
'd:\\boost\\boost_1_38_0\\boost\\config\\abi_prefix.hpp' : 
alignment changed after including header, may be due to missing 
#pragma pack(pop)

Some experimentation reveals that including thread.hpp before winsock2.h triggers all these warnings. The simple solution is to just move #include <boost/thread.hpp> down below #include <winsock2.h>.