Have you been able to use LW before without a problem?
What security or antispyware programs are you using? Some antispyware will see LW as a threat & stop it from working. Make sure LW's on the list of exceptions/allowed apps of your security programs.

Did you make sure to install Java first, then reinstall LW?
Did you have any problems finding the preferences folder (sometimes people can't find it as it's a hidden folder)?

Your Pro is an official version from www.limewire.com right??