you need to give the specifications of your machine - OS, RAM, LW version, firewall status, net connexion details for better help.
check if your java version is up-to-date from
http://www.java.com/en/download/installed.jsp if not plz dwnload the latest version.
uninstalling limewire will not cause the music files that you already have to be deleted, coz they are stored on your hard disk.
you may lose your incomplete files that are older than 7 days, coz thats the default setting in LW.
also check and clean your machine for any viruses, spyware, adware or malware.
after you have installed the new java version, delete any limewire related files on ur machine [find files named filewire in windows and then delete them]. then reinstall LW, get the latest version 4.9.37 from limewire's site.
so -
1.uninstall Limewire
2.load latest java version
3.delete .limewire folder [found in c:\documents and settings folder in most versions of windows, found in c:\windows in win98]
4.install new version of limewire. dwnload the full installer from LW site, rather than the online downloader.
hope this helps, stay safe.