Any ideas? I think they're related to ICU. I downloaded ICU 3.6 (the latest). However, I am using this with VS2005, which was "rarely tested" according to the website. Still, after converting the ICU project to VS2005 and building, I had no build errors, but I do get these link errors with boost, which all seem to be ICU-related. See below: -------------- D:\3rdparty\boost_1_34_0>call "C:\Program Files\Microsoft Visual Studio 8\VC\vcvarsall.bat" x86 Setting environment for using Microsoft Visual Studio 2005 x86 tools. Building Boost.Regex with Unicode/ICU support enabled Using ICU in D:\3rdparty\icu4c-3_6/include ...patience... ...patience... ...found 5406 targets... ...updating 10 targets... msvc.link.dll bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.dll bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.lib Creating library bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.lib and object bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.exp icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall icu_3_6::Locale::~Locale(void)" (__imp_??1Locale@icu_3_6@@UAE@XZ) referenced in function __unwindfunclet$??0icu_regex_traits_implementation@re_detail@boost@@QAE@ ABVLocale@icu_3_6@@@Z$0 icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: static class icu_3_6::Collator * __cdecl icu_3_6::Collator::createInstance(class icu_3_6::Locale const &,enum UErrorCode &)" (__imp_?createInstance@Collator@icu_3_6@@SAPAV12@ABVLocale@2@AAW4UErrorC ode@@@Z) referenced in function "public: __thiscall boost::re_detail::icu_regex_traits_implementation::icu_regex_traits_impl ementation(class icu_3_6::Locale const &)" (??0icu_regex_traits_implementation@re_detail@boost@@QAE@ABVLocale@icu_3 _6@@@Z) icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall icu_3_6::Locale::Locale(class icu_3_6::Locale const &)" (__imp_??0Locale@icu_3_6@@QAE@ABV01@@Z) referenced in function "public: __thiscall boost::re_detail::icu_regex_traits_implementation::icu_regex_traits_impl ementation(class icu_3_6::Locale const &)" (??0icu_regex_traits_implementation@re_detail@boost@@QAE@ABVLocale@icu_3 _6@@@Z) icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall icu_3_6::Locale::Locale(void)" (__imp_??0Locale@icu_3_6@@QAE@XZ) referenced in function "public: __thiscall boost::icu_regex_traits::icu_regex_traits(void)" (??0icu_regex_traits@boost@@QAE@XZ) icu.obj : error LNK2019: unresolved external symbol _u_tolower_3_6 referenced in function "public: unsigned __int64 __thiscall boost::icu_regex_traits::lookup_classname(int const *,int const *)const " (?lookup_classname@icu_regex_traits@boost@@QBE_KPBH0@Z) icu.obj : error LNK2019: unresolved external symbol _u_toupper_3_6 referenced in function "public: int __thiscall boost::icu_regex_traits::toupper(int)const " (?toupper@icu_regex_traits@boost@@QBEHH@Z) icu.obj : error LNK2019: unresolved external symbol _u_digit_3_6 referenced in function "public: bool __thiscall boost::icu_regex_traits::isctype(int,unsigned __int64)const " (?isctype@icu_regex_traits@boost@@QBE_NH_K@Z) icu.obj : error LNK2019: unresolved external symbol _u_isspace_3_6 referenced in function "public: unsigned __int64 __thiscall boost::icu_regex_traits::lookup_classname(int const *,int const *)const " (?lookup_classname@icu_regex_traits@boost@@QBE_KPBH0@Z) icu.obj : error LNK2019: unresolved external symbol _u_charFromName_3_6 referenced in function "public: class std::vector<int,class std::allocator<int> > __thiscall boost::icu_regex_traits::lookup_collatename(int const *,int const *)const " (?lookup_collatename@icu_regex_traits@boost@@QBE?AV?$vector@HV?$allocato r@H@std@@@std@@PBH0@Z) icu.obj : error LNK2019: unresolved external symbol _u_isblank_3_6 referenced in function "public: bool __thiscall boost::icu_regex_traits::isctype(int,unsigned __int64)const " (?isctype@icu_regex_traits@boost@@QBE_NH_K@Z) icu.obj : error LNK2019: unresolved external symbol _u_charType_3_6 referenced in function "public: bool __thiscall boost::icu_regex_traits::isctype(int,unsigned __int64)const " (?isctype@icu_regex_traits@boost@@QBE_NH_K@Z) bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.dll : fatal error LNK1120: 11 unresolved externals call "C:\Program Files\Microsoft Visual Studio 8\VC\vcvarsall.bat" x86 >nul link /NOLOGO /INCREMENTAL:NO /DLL /DEBUG /subsystem:console /out:"bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex -vc80-mt-gd-1_34.dll" /IMPLIB:"bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_re gex-vc80-mt-gd-1_34.lib" @"bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc8 0-mt-gd-1_34.dll.rsp" if %ERRORLEVEL% NEQ 0 EXIT %ERRORLEVEL% if exist "bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80 -mt-gd-1_34.dll.manifest" ( mt -nologo -manifest "bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80 -mt-gd-1_34.dll.manifest" "-outputresource:bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\ boost_regex-vc80-mt-gd-1_34.dll;2" ) ...failed msvc.link.dll bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.dll bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.lib... ...removing bin.v2\libs\regex\build\msvc-8.0\debug\threading-multi\boost_regex-vc80- mt-gd-1_34.lib ...skipped <pstage\lib>boost_regex-vc80-mt-gd-1_34.dll for lack of <pbin.v2\libs\regex\build\msvc-8.0\debug\threading-multi>boost_regex-vc8 0-mt-gd-1_34.dll... ...skipped <pstage\lib>boost_regex-vc80-mt-gd-1_34.lib for lack of <pbin.v2\libs\regex\build\msvc-8.0\debug\threading-multi>boost_regex-vc8 0-mt-gd-1_34.lib... ...skipped <pstage\lib>boost_regex-vc80-mt-gd.lib for lack of <pstage\lib>boost_regex-vc80-mt-gd-1_34.lib... msvc.link.dll bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.dll bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.lib Creating library bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.lib and object bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.exp icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall icu_3_6::Locale::Locale(class icu_3_6::Locale const &)" (__imp_??0Locale@icu_3_6@@QAE@ABV01@@Z) referenced in function "public: class icu_3_6::Locale __thiscall boost::re_detail::icu_regex_traits_implementation::getloc(void)const " (?getloc@icu_regex_traits_implementation@re_detail@boost@@QBE?AVLocale@i cu_3_6@@XZ) icu.obj : error LNK2019: unresolved external symbol _u_tolower_3_6 referenced in function "public: int __thiscall boost::icu_regex_traits::translate_nocase(int)const " (?translate_nocase@icu_regex_traits@boost@@QBEHH@Z) icu.obj : error LNK2019: unresolved external symbol _u_toupper_3_6 referenced in function "public: int __thiscall boost::icu_regex_traits::toupper(int)const " (?toupper@icu_regex_traits@boost@@QBEHH@Z) icu.obj : error LNK2019: unresolved external symbol _u_digit_3_6 referenced in function "public: int __thiscall boost::icu_regex_traits::value(int,int)const " (?value@icu_regex_traits@boost@@QBEHHH@Z) icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: __thiscall icu_3_6::Locale::Locale(void)" (__imp_??0Locale@icu_3_6@@QAE@XZ) referenced in function "public: class icu_3_6::Locale __thiscall boost::icu_regex_traits::getloc(void)const " (?getloc@icu_regex_traits@boost@@QBE?AVLocale@icu_3_6@@XZ) icu.obj : error LNK2019: unresolved external symbol _u_isspace_3_6 referenced in function "public: bool __thiscall boost::icu_regex_traits::isctype(int,unsigned __int64)const " (?isctype@icu_regex_traits@boost@@QBE_NH_K@Z) icu.obj : error LNK2019: unresolved external symbol _u_isblank_3_6 referenced in function "public: bool __thiscall boost::icu_regex_traits::isctype(int,unsigned __int64)const " (?isctype@icu_regex_traits@boost@@QBE_NH_K@Z) icu.obj : error LNK2019: unresolved external symbol _u_charType_3_6 referenced in function "public: bool __thiscall boost::icu_regex_traits::isctype(int,unsigned __int64)const " (?isctype@icu_regex_traits@boost@@QBE_NH_K@Z) icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: virtual __thiscall icu_3_6::Locale::~Locale(void)" (__imp_??1Locale@icu_3_6@@UAE@XZ) referenced in function __unwindfunclet$??0icu_regex_traits_implementation@re_detail@boost@@QAE@ ABVLocale@icu_3_6@@@Z$0 icu.obj : error LNK2019: unresolved external symbol "__declspec(dllimport) public: static class icu_3_6::Collator * __cdecl icu_3_6::Collator::createInstance(class icu_3_6::Locale const &,enum UErrorCode &)" (__imp_?createInstance@Collator@icu_3_6@@SAPAV12@ABVLocale@2@AAW4UErrorC ode@@@Z) referenced in function "public: __thiscall boost::re_detail::icu_regex_traits_implementation::icu_regex_traits_impl ementation(class icu_3_6::Locale const &)" (??0icu_regex_traits_implementation@re_detail@boost@@QAE@ABVLocale@icu_3 _6@@@Z) icu.obj : error LNK2019: unresolved external symbol _u_charFromName_3_6 referenced in function "public: class std::vector<int,class std::allocator<int> > __thiscall boost::icu_regex_traits::lookup_collatename(int const *,int const *)const " (?lookup_collatename@icu_regex_traits@boost@@QBE?AV?$vector@HV?$allocato r@H@std@@@std@@PBH0@Z) bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.dll : fatal error LNK1120: 11 unresolved externals call "C:\Program Files\Microsoft Visual Studio 8\VC\vcvarsall.bat" x86 >nul link /NOLOGO /INCREMENTAL:NO /DLL /subsystem:console /out:"bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_reg ex-vc80-mt-1_34.dll" /IMPLIB:"bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_ regex-vc80-mt-1_34.lib" @"bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-v c80-mt-1_34.dll.rsp" if %ERRORLEVEL% NEQ 0 EXIT %ERRORLEVEL% if exist "bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc 80-mt-1_34.dll.manifest" ( mt -nologo -manifest "bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc 80-mt-1_34.dll.manifest" "-outputresource:bin.v2\libs\regex\build\msvc-8.0\release\threading-mult i\boost_regex-vc80-mt-1_34.dll;2" ) ...failed msvc.link.dll bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.dll bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.lib... ...removing bin.v2\libs\regex\build\msvc-8.0\release\threading-multi\boost_regex-vc8 0-mt-1_34.lib ...skipped <pstage\lib>boost_regex-vc80-mt-1_34.dll for lack of <pbin.v2\libs\regex\build\msvc-8.0\release\threading-multi>boost_regex-v c80-mt-1_34.dll... ...skipped <pstage\lib>boost_regex-vc80-mt-1_34.lib for lack of <pbin.v2\libs\regex\build\msvc-8.0\release\threading-multi>boost_regex-v c80-mt-1_34.lib... ...skipped <pstage\lib>boost_regex-vc80-mt.lib for lack of <pstage\lib>boost_regex-vc80-mt-1_34.lib... ...failed updating 4 targets... ...skipped 6 targets... -------------------- Thanks in advance for any help that can be provided, Lawrence