Hi pye..Sorry about the delay...
I'd say it's Talk Talk as they are known for Throttling p2p connections...
::. Kitz - ISP Caps, FUPs and Prices .::
You could try changing your port numbers...
Go To Tools > Options > Advanced > Firewall and change to the manual port forward and enter 64049 and also the listen port number to 64049 and select apply....
You could try deleting your preference folder if the above does not work, This will give you a fresh start as the olf folder may have a corruption within...
Fixes for Limewire when LW isn't operating as it should
You could also try uninstalling your Java from the add/remove programs and then re-install the JRE 5.11 offline version....
Archive: Download Java 2 Platform Standard Edition (J2SE) 5.0 Update 11