When I save my .w file with Windows line endings (CR LF pairs), it keeps nuweb from correctly getting the names of macros (lots of "never defined" and "never referenced" errors). When I save it with Unix line endings (LF only), everything works fine.
Perhaps I should clarify: .w files with Windows line endings caused errors when I compiled nuweb on OS X.
I have never tried nuweb on Windows, and I do not know if nuweb compiled for Windows would have errors with a file with Windows line endings.