[boost] lexical_cast.hpp:102: error: `wstring' is not a member of `std' ?

Hello, I'm not a boost expert, but I'm using LyX, which has boost (version 1.31.0) included in its source code. I have FreeBSD (4.10) and use gcc 3.4.2. When I compile LyX, I get an error from boost: [...] ../../boost/boost/lexical_cast.hpp:102: error: `wstring' is not a member of `std' ../../boost/boost/lexical_cast.hpp:102: error: `wstring' is not a member of `std' ../../boost/boost/lexical_cast.hpp:103: error: template argument 1 is invalid ../../boost/boost/lexical_cast.hpp:103: error: explicit specialization of non-template `<type error>' ../../boost/boost/lexical_cast.hpp:162: error: declaration of `operator>>' as non-function ../../boost/boost/lexical_cast.hpp:162: error: expected `;' before '(' token ../../boost/boost/lexical_cast.hpp:168: error: expected `;' before "private" When I reported this to the LyX list, I was told to forward the problem to the boost list. There may be a problem here with FreeBSD, gcc 3.4.2 and boost. Any idea what is going on here? Thanks, Rob.