I presume you are using windows xp or later right?
Do you have the most recent Java update?

Try this version & see if same issue: LimeWire 5.2.2 (Beta) - Lime Wire

Other than that, see points 3, 5 & 6 here: Fixes for Limewire (click on blue link). Keep in mind about point #3 that you should backup your downloads.dat file before deleting the preferences file.