Is your LW connected properly (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 here.
If LW Will Not Connect
If nothing there helps, post back with your system details

The orange warning banner with the padlock was originally added because there was a bogus LW update showing up in search results & if people downloaded it, they could end up infected. To try to prevent people from downloading a dangerous file, the warning banner was added.

Now, if you click on the banner it seems to warn you of a security problem & tell you that you need to update...heaps of people have been having trouble with the update so I'd say don't do it Use the forum search to look for update to see the problems that people are having.