If you have pro then you still have the installer right? Since Pro only comes in the "Offline" installation anyway. I can think of 2 possibilities.
1. You are running a spyware program that is not p2p friendly & thinks all/some p2p programs are spyware when they are not. Answer is to put LW on the exception list or else, get a reliable spyware program that is safe to use with p2p programs. Have a look at WARNING: Viruses on network you should be aware of! (click on link) for our recommended ones.

2. Your Java is causing issues. (a) I would uninstall all versions of Java & reinstall only using the "Offline" installer which is about 13-15 MB in size. (b) Delete your LW Prefs folder. (c) if still problems, try the various compabitibility modes. For b & c see instructions here Fixes for Limewire. As for c, which java to install? Some Pro users have had problems using Java 1.6, but have solved it by going back to Java 1.5. So might I suggest yo utry the same thing: Java 1.5 (take the JRE) which is about 4th on the list. Remember to download the Offline version (2nd) & not the online installer.