Useful tip: Use mozilla. With mozilla you can view the values of the cookies using the browser functionality. You can also make it so it warns if you a cookie is being set.

I've experienced similar problems, my problems were around the domain and path settings..

Also if you're using CGI::Application you might want to use redirect rather than using header.

As previously mentioned, you should never, ever, ever put information in your cookie other than a session id, which is mapped to the user serverside. All the information you require, can and should be stored serverside.