Yesterday, I tried upgrading from Boost 1.30 to 1.33 and I got the weirdest reaction from my linker. Some background: I am using MSVC6SP6; The code in question is a dll that runs under PharLap 9.1. I am linking against libcmt as well as a lib called cellexe.lib, which provides all of the C runtime stuff and PharLap-specific OS stuff. With Boost 1.30, everything compiles and links just peachy. When I pointed the project at Boost 1.33, I had to make a couple of small code changes: 1. I had to change boost::mpl::apply_if to boost::mpl::eval_if. 2. I had to stop using TrivialIteratorConcept and switched to ForwardIteratorConcept or RandomAccessIteratorConcept. That's really the only code changes I can think of but now my linker gives me a bunch of warnings and 1 error message, which is what's really killing me: Linking... LIBCMT.lib(typinfo.obj) : error LNK2005: "const type_info::`vftable'" (??_7type_info@@6B@) already defined in cellexe.lib(Cellexe.exe) LIBCMT.lib(strtol.obj) : error LNK2005: _strtoul already defined in cellexe.lib(Cellexe.exe) LIBCMT.lib(chkstk.obj) : error LNK2005: __chkstk already defined in cellexe.lib(Cellexe.exe) LIBCMT.lib(xtoa.obj) : error LNK2005: __ultoa already defined in cellexe.lib(Cellexe.exe) LIBCMT.lib(atox.obj) : error LNK2005: _atoi already defined in cellexe.lib(Cellexe.exe) LIBCMT.lib(typinfo.obj) : warning LNK4006: "const type_info::`vftable'" (??_7type_info@@6B@) already defined in cellexe.lib(Cellexe.exe); second definition ignored LIBCMT.lib(strtol.obj) : warning LNK4006: _strtoul already defined in cellexe.lib(Cellexe.exe); second definition ignored LIBCMT.lib(chkstk.obj) : warning LNK4006: __chkstk already defined in cellexe.lib(Cellexe.exe); second definition ignored LIBCMT.lib(xtoa.obj) : warning LNK4006: __ultoa already defined in cellexe.lib(Cellexe.exe); second definition ignored LIBCMT.lib(atox.obj) : warning LNK4006: _atoi already defined in cellexe.lib(Cellexe.exe); second definition ignored Creating library PharLapRelease/Devo.lib and object PharLapRelease/Devo.exp LIBCMT.lib(crt0.obj) : error LNK2001: unresolved external symbol _main PharLapRelease/Devo.dll : fatal error LNK1120: 1 unresolved externals Error executing link.exe. I can't understand why the linker is now searching for _main when the project is a dll and I have all the necessary stuff: .def file, /dll switch, etc. I have compiled and run this dll for literally years when using Boost 1.30. Can anyone think of anything in this Boost library upgrade that could cause this? Keep in mind that I did not change any project setting other than the include directories to point the compiler at the directories containing Boost 1.33 and that I have been using this code along with Boost 1.30 for years.