As a first suggestion I'd say try deleting LW's preference folder with LW completely shut down. See points 2 & 3 in this thread:
Fixes for Limewire. This will reset all your option settings, so make a note of them first.
Getting information about your modem/router that you use to connect to the internet would be rather important in case the above advice doesn't solve the problem..
Cheers
FOTH