What version of LW are you using? Which version of Java are you using? Click on Help > about LW & you'll see.

Try updating Java, see if that helps with the freezing. Download the JRE offline installer & remove any other Java versions installed (Add/Remove Programs) before you install the new one.
Java SE Downloads

Are you using Vista?????? If you are, check out these threads about files not showing.
http://www.gnutellaforums.com/genera...ng-libary.html
http://www.gnutellaforums.com/genera...utside-lw.html

If you're using LW 4.16 with XP, have a look for your recently downloaded files in C:\Documents and Settings\your username\Limewire Saved ...are the new downloads there? Or look in C:\Documents and Settings\your username\Shared.
Else, use your computer's search to look for some of the file names...do they show up anywhere?