Did you install using the english or international (multilingual) installer. These are different installers & the latter will force LW to use Java 1.3 which can cause issues. Later Java is better.
May I suggest you try the beta 4.3.3 which overcomes a no. of bugs that LW 4.2 has. It can be found here:
http://www.limewire.com/english/content/beta.shtml
You should uninstall using the Add/Remove programs control panel beforehand.
It might also be an idea to delete your LW preferences folder again before you install.