Cannot convert to MP3 in Itunes
 

No problems for a long time. Then, suddenly, with no changes made by me, every song I download from Limewire gets the same message on ITunes. Cannot convert to MP3, nor can I drop any of the songs that I downloaded AS Mp3s into the library. What to do? I did download the "associator" and have tried converting files with the help of that software, but to no avail.