I have had issues with Eclipse's way of handling plugin settings, which resulted in a very subtle error that prevented me from building WINSCW targets.
I have installed Carbide.c++ 1.1 Express, then I have installed Carbide.c++ 1.1 Professional alongside with Express Edition. Second instance was set up to use the same workspace. When I uninstalled Express version, Professional stopped producing WINSCW build with linking errors (apparently unable to find any static libraries). Turned out that MWSYM2* environment variables are pointing to (non-existent) Express' directory, because the variable was pulled from <workspace>\.metadata\.plugins\org.eclipse.core.runtime\.settings\org.eclipse.cdt.managedbuilder.core.prefs which still contained the outdated path. Deleting this file solves the problem.