The specified CGI application misbehaved by not returning a complete set of HTTP headers.

CGI Error
The specified CGI application misbehaved by not returning a complete set of HTTP headers.

When my php script starts download of a file - downloading begins and stops at 143360 bytes, then it freeze and a few minutes later I'm getting this error...
So I can't download the file from FTP... How can I resolve this problem?
the source code:
$ftp = new ftp('myftpserver.com', 21, 'ftp_user', 'ftp_password', 1);
$ftp->setDownloadDir('e:\\web\\motorcarsor\\htdocs\\');
if ((file_exists('e:\\web\\motorcarsor\\htdocs\\VEHICLES.txt')))
$ftp->setResumeDownload(true);// (or false - no matter)
$ftp->get('VEHICLES.txt', '');