Salut du Québec Steppers! I will ask you something to try that might help your situation:
First try to change the theme in LW to the limewire theme. Menu Display -> Apply theme -> Limewire theme. Try to add a share in options.
If that doesn't work:
-uninstall java 1.5 while LW is shut down
-install java 1.4 instead :
http://java.sun.com/j2se/1.4.2/download.html (download the JRE)
-start LW and tell us if the buttons work
I tell you that because java 1.5 on XP uses the default XP appearance. Java 1.4, on the other end, uses by default the limewire theme (different innner working). The appearance should be different for your LW, but that might help you to finally activate buttons.
Ciao
