You see after cpan[1]> install HTML::Tree see all those ...? Thats when all that happens, when it tells you what you're missing (it doesn't actually check to see that its not broken, just present).
Thanks. It was a little bit confusing figuring out what order all the modules mentioned in the error messages should be installed in. This is the order that worked for me:
1) HTML::Parser
2) HTML::TreeBuilder
3) HTML::Element (a message said it was up to date)
4) HTML::Tree (a message said it was up to date)