It sounds a bit suss for your ISP, it's like their shaping you after a certain download limit is reached...
But you could try these fixes and see if they help...
Try uninstalling all versions of 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
If that does not help with your problem try deleting your preference folder/s...This will reset your configurations back to default and get rid of any corruption that may of happened...
Fixes for Limewire when LW isn't operating as it should