POST using libcurl hangs -

i've got libcurl application written in msc++, works fine except 1 client experiencing this: when app post (about 172k buffer) headers returned include "content-length: 0" hangs. normally, content-length: xxxx xxxx byte count of uploading. libcurl version 7.27.0. don't know if coincidence or not, on connection attempt, client got " connection #0 seems dead!" libcurl reconnects , authenticates. tried simulating situation putting long delay before post. got error message, had no problem doing post.