Different Connection Problem

[DUtrainertom]

Okay, so I've never had problems in the past with Limewire. About a week ago I began having problems connecting. I'll open the program and manually connect (but I've also tried the automatic). The system will begin getting IP's from other users on the network, but won't connect for more than 5-10 seconds before being dropped. Limewire will go on like this for about 2-5 minutes before finally popping up the dreaded cannot connect window. I've tried everything posted here all to no avail. I've even talked to my school's IT guy and he has no clue. Help!

System Info:
-Windows XP Pro SP1 updated
-Sony Vaio Z1 laptop
-running on a LAN (school) with multiple T1's.
-currently running 4.0.7 but have run 4.1.1 and 4.1.2.
-have updated Java multiple times.
-LAN has an MS ISA firewall, but the port 6346 is open and I'm running ISA firewall client provided by the school.
-school is located in the Cayman Islands.

Any suggestions people? I'm at my wits end!

Thanks!