[Addendum...] Following my original post, firstly, apologies - I should have mentioned that I'm trying to build the regex example using Visual Studio 8 Express Edition (i.e. VC++2005). Also, I've got some more information.... Apart from those libs that I mentioned in my original post, I've found a whole bunch of libs beginning with "libboost-regex-vc80-" and ending with these suffixes:- mt-1_40.lib mt-gd-1_40.lib mt-s-1_40.lib mt-sgd-1_40.lib s-1_40.lib I guess these must be the static link libs. Anyway, I've discovered that if I link to any lib that ends in "mt-1_40.lib" I can build my app and launch it successfully as long as I build in Release mode. But in Debug mode, the app either doesn't launch - or if it does launch, it gives the unhandled exception that I described earlier. Hope that helps, John