i had the same issue 2-3 days back. Was listening music in Nokia Music, and when i pressed the lock button the phone wasnt turning on but the song kept playing. I tried doing the soft reset, but nothing happened. Irritated i decided to remove the battery, but after a few seconds, it rebooted on its own...!!!!! Dont know what could be cause....
Speaking about music, has anyone of you have multiple tracks of the same song on your phone but only a single copy in the memory card...... I had around 300 songs in my memory card but both Music+Videos and Nokia Music showed around 500 tracks. After formatting the card, i downloaded around 160 songs from Nokia music and now i have 1200 songs......!!!!!!! Do you guys have any ideas about it???????