Hi, I have a Samsung Yp-U3 and lately it has not been accepting certain songs. I could not figure out what these songs had in common for the life of me. Then suddenly today, after analyzing the situation one again, I figured it out. If the song has the same title as the title of the CD, it will NOT accept that song. Example would be the name of the CD is Daybreaker, the song it will not accept is Daybreaker. All you have to do is rename the song and it will accept it. The slightest change will work. Going from Daybreaker to Daybreak will work just as well.
If you are experiencing a simmilar problem with your U3, look and see if the songs have that factor. I wanted to let others know, so they don't end up like me, pulling my hair out of my head.