Your college may be blocking the ports that Gnutella uses for file-sharing. Many other users such as yourself have experienced this.
If you know that this is NOT the case, you might try an alternate version that fixes connection problems related to software incompatabilities. This began when LimeWire switched to the 1.3.1 JRE.
To download, go here:
http://www9.limewire.com/download/LimeWire16d118.exe
For more info, go here:
http://www.gnutellaforums.com/showth...&threadid=2963