You might want to update your LW and java. They're both outdated. If you want to save LW 4.8.1, just move the installer called LimeWireWin4.8.1.exe out of your program folder to someplace you can find it like your documents folder. That way you can always go back to it if you want.
Get the latest LW version here:
Lime Wire » Download LimeWire
For java try uninstalling your current version of java from the add/remove programs and then d/load and install Java Runtime Environment (JRE) 5.0 Update 12(use the offline installer):
Java SE Downloads - Previous Release - JDK 5
You might also need to portforward your router. Instructions here:
Port Forwarding for the Thomson/Alcatel SpeedTouch 530