Here's a suggestion, not perl related.

In the standard config setup there's a "BrowserMatch" declaration that forces 1.0 negotiations with certain MSIE browsers -- used to be just the "MSIE 4\.0b" regex that it would look for but I've seen recommendations to make this match all MSIE browsers. In any event, look for BrowserMatch directives in httpd.conf that include downgrade-1.0 and/or force-response-1.0 operations.