Limewire had been working great downloading files, until I switched my method connection from dial-up to cable. Now they download even faster than before, but they won't play once they are complete. Normally if I clicked "Launch" it would open up the song in ITunes, but now nothing happens. What's the deal? Please help!

Couple of possibilities here. Either Limewire no longer recognizes itunes as your default player or the cable software is changing the type or creator code of your files to something itunes doesn't recognize. Do the files play OK if imported directly into itunes? If not, then you will need to change the resource info to "mp3" and "hook" using an app like resedit or techtool lite.
I don't know how Limewire recognizes which mp3 player to launch. I don't see anything in the preferences for this.
Hope some of this helps