DMF3.5 - Add MP3 into background music (error)

[Bear999]

Hi. I am trying to create a video slideshow but have encountered the following problem. When I click on background music, some of the mp3 which I previously converted from cd (note, the mp3 are playable in window media player and all other mp3 player) will not load in there. My program will then hanged and go back to the main menu. But when i add in some mp3 downloaded from the internet, it can load properly.

Help. Any idea why? Hope some kind folks can help me on this.