That might be because your college blocks p2p sharing programs or at least shapes the bandwidth available. Most schools nowadays are blocking p2p use. See A Fix for those whose ISP's block Limewire pages 1 - 3 which has a link to alternative instructions. See if that helps.

Using your browser go here: http://www3.limewire.com:6346/ The page should say 'Your test worked!'. What happens when you go there?
If you can't get the page, then open LW & try a different port test here: http://home.no.net/tgrumpy/ct/dex.php
Here's some other ports to try: 1111, 3500, 4008, 1203, 80, 20282, 10000, 443, 40475.
To change it within LW, go to LW's Preferences>Advanced>Firewalls & change the listening port from 6346 to one of the above. Press apply after the change, then go to menu bar, File>Connect.