In the name of Allah, Most Compassionate, Most Merciful,
The worst case scenario in the event of being inflicted with a disease is when the one involved refuses to believe that he has been inflicted with that disease. The way this phenomenon is accepted and recognised in diseases and illnesses that affect the physical body, it is also true with regards to spiritual diseases and ailments.
When a person commits a sin (may Allah save us all) believing that a sin is being committed and feels regret and remorse in the heart, then this is far better then committing the sin and believing it to be lawful (halal). In the former situation, only one sin is being committed, and it is very likely that the individual may repent out of the remorse felt in the heart. In the latter case, however, in addition to the sin being committed, there is the greater sin of trying to justify it. Normally, such an individual does not receive the guidance to repent from his sin. (May Allah save us all, Ameen).
Music and Singing?
The case with music and unlawful singing is the same. It has been decisively prohibited in Shariah, as the evidences mentioned further along will show. Yet there are individuals that are not ready to believe that it is Haram.
In the modern era, music has spread to such an extent that nobody is free from it. Individuals are confronted with situations where they are forced to listen to music. It is played nearly in all department stores and supermarkets. If you sit in a taxi, make a phone call or even walk down the street, you will not be saved from this evil. Young Muslims drive around in their cars with the music fully blasted. The increasing popularity of music, which is prevalent in our society, poses a great threat to the Muslims.
Music is a direct ploy of the Non-Muslims. One of the main causes for the decline of the Muslims is their involvement in useless entertainment. Today we see that Muslims are involved, and at the forefront perhaps, of many immoralities and evils. The spiritual power which once was the trait of a Muslim is nowhere to be seen. One of the main reasons for this is music and useless entertainment.
Harms and effects of music
We should be aware that nothing has been prohibited by the Almighty Creator except that which is harmful to the Muslims and the society as a whole. There are great harms and ill-effects of music.
Rest of the answer can be read here http://qa.sunnipath.com/issue_view.asp?HD=1&ID=1786