Whenever I do a search, the window shows that it is searching but nothing shows up on the screen. What's wrong?

Is your LW properly connected (all green/blue connection bars)?? If LW's connected, try the fixes below.

1. In LW go tools > options > searching > basic & check whether the 'show license warning' box is ticked. If it does, untick it > Apply > ok...see if that makes any difference.

2. Problems with the search

3. Delete LW's preferences folder when LW's properly closed. See point 3 here & also point 2 if you've used older versions of LW in the past (there could be a folder in either location).
Fixes for LimeWire
This will change all of your settings within LW's options, you'll have to go back through afterwards & reset things to the way you like them.
Vista users: LimeWire Pref Folder in Vista

If LW's not connected, try the fixes in the post below. If nothing there helps, post back with your system details
If LW Will Not Connect

If the other suggestions don't work, try opening Limewire and right clicking on the "search" pane. You should be given an option of additional searches. Hope this helps.
Good luck.