I've used a previous version of the boost regex library before and have just upgraded to the latest version. Built the libs and dll fine, but now I get a A/V when calling any boost code. I've even set up a vanilla console app with all the Borland default settings and the following code: #include "boost/regex.hpp" int main(int argc, char* argv[]) { boost::wregex regExpr2(L"bill.*"); bool result; result = boost::regex_match(L"freddy", regExpr2); result = boost::regex_match(L"billabong", regExpr2); return 0; } And it blows up on the first regex_match!! I can't figure out what's going on - I know it's linking to the _sdi version of the lib because it complains about it being missing if I remove it, and the dlls are on the path and are loaded as soon as this mini-app starts up. It makes no difference whether I build through the command line or in BCB GUI. Please help!! Thanks, Tim D.