Hartmut, applying your patch from the CVS head (which you produced in request to multi-thread safety and conditional preprocessing) results in linking problems. I tried compiling with boost_1_34_0 and boost_1_34_1_RC2. Here are some of the errors which are produced by the linker. The interesting thing is that threading library is compiled fine. instantiate_cpp_exprgrammar.obj : error LNK2001: unresolved external symbol "public: virtual __thiscall boost::lock_error::~lock_error(void)" (??1lock_error@boost@@UAE@XZ) instantiate_cpp_grammar.obj : error LNK2001: unresolved external symbol "public: virtual __thiscall boost::lock_error::~lock_error(void)" (??1lock_error@boost@@UAE@XZ) instantiate_cpp_literalgrs.obj : error LNK2001: unresolved external symbol "public: virtual __thiscall boost::lock_error::~lock_error(void)" (??1lock_error@boost@@UAE@XZ) instantiate_defined_grammar.obj : error LNK2001: unresolved external symbol "public: virtual __thiscall boost::lock_error::~lock_error(void)" (??1lock_error@boost@@UAE@XZ) With Kind Regards, Ovanes Markarian