I think you've got the problem sorted, but one bit of advice: use CGI::Carp qw(fatalsToBrowser); You'll get errors sent to the browser.

This has saved me SO MUCH time. My script ran fine through the shell, and it gave me 500 Internal Server Error when ran over the web. I eventually tracked the problem down to FreeBSD not liking Windows/DOS' text file linebreaks and invalid use of regexp metacharacters in a regexp.