Music will not play in Windows Media Player Library

[asana]

Greetings!

I have a problem with using Limewire in regards to moving the music that have downloaded from the temporary folder to MY Libray in Media Player. Once I download the music to a new playlist in my libray, I then go back and delete it from the temporary folder, then when I come back and try and play the music, it all starts highlighting in red and will not allow me to play the songs at all. Most of the music I download to my libray does this(not all)...Does this mean that I need to keep the temp folder in order to play these songs, and if this is the case, if Limewire suddenly crashed or whatever, wouldn't I lose all my songs in the temp folder? Why can I not play these songs highlighted in red and if they are highlighted, then I surely cannot transfer them to mp3 player or even burn them.
Can anyone please help me with this?