One last attempt: according to http://www.boost.org/libs/iostreams/doc/installation.html, NO_ZLIB is by default 1 under windows. I define -DNO_ZLIB=0 when I build boost, and the problem persists. What irritates me is that there should be some warning if zlib is not used, and if it is not used, the file should not be compressed at all....
Bo
