Using of HTML::Form unlikely to fix a problem as this module internally uses LWP::UserAgent.

I'm not sure but this problem could be related to new HTTP/1.1 support code in latest versions of LWP. You may try to set environment variable PERL_LWP_USE_HTTP_10 before running your script. See perldoc LWP for details.

--
Ilya Martynov (http://martynov.org/)