Hi, I have a large project and for what ever reason if I add xpressive.hpp in my precompiled header, it completly kills intelligence. So I figured I'd move the stuff I want to use off to a lib. Works fine in debug but if I build the release, this lib tries to link in the Microsoft debug libs. In my project: 1>mfcs90.lib(nolib.obj) : warning LNK4098: defaultlib 'mfc90d.lib' conflicts with use of other libs; use /NODEFAULTLIB:library 1>mfcs90.lib(nolib.obj) : warning LNK4098: defaultlib 'mfcs90d.lib' conflicts with use of other libs; use /NODEFAULTLIB:library and just this one in the test solution: 1>msvcrt.lib(cinitexe.obj) : warning LNK4098: defaultlib 'msvcrtd.lib' conflicts with use of other libs; use /NODEFAULTLIB:library I have been able to recreate the problem in a small solution that should not dependent on my directories other than setting the boost path: http://lakeweb.net/downloads/RaVpath.zip (20k) vc 2008 (9.0) boost 1_42 And I don't know, this may have nothing to do with boost, but I have other dlls and libs without this problem. It is coming from 'boost::filesystem' as best as I can determine. And maybe someone has seen this before and knows off the top of their head. Thanks, Dan.