As Grandpa said in your other posts...maybe your school has started blocking p2p. Have you asked network/computer admin if they've started blocking p2p? Do other students use p2p successfully?
Do this test & see if it works. If it doesn't, means that LW's default port's being blocked
http://www3.limewire.com:6346

You could try using the forum search to look for school connection or something similar.