It might well be worth uninstalling it & starting over. But update your Java BEFORE re-installing LW:
Java 1.5 (take the JRE)
And also delete the LW Preferences folder called
.limewire (whilst LW is closed!) & found here: Windows NT 4.0 / 2000 / XP: C:/Documents And Settings/your_username/.limewire OR Windows 98 / ME: Your .limewire folder is in "C:\My Documents" (BUT make a note of all your LW settings 1st, b/c after you delete the LW prefs folder you'll need to reset them.)
It may also be worth defragmenting your hard disk drive.