One question: Are you behind a proxy?

Well, two: Did you look at the PPM help file that comes with Activestate's Perl (should be installed locally, or you can find the PPM-specific page at http://aspn.activestate.com/ASPN/Reference/Products/ActivePerl/faq/ActivePerl-faq2.html.

Usually, with trouble like you describe, I find that it's a proxy issue, and the help file details how to configure PPM to work with proxies.