Originally Posted by Jamolah
So I thought this was an issue with the music being on the external SD card and when removed/re-mounted it caused the Playlist to lose track of the file location. So I decided to move all my music to the internal memory card. And at first everything was working fine, but now I'm getting the "Playback Error: Couldn't play your media". And when I look at the songs, it seems they're all duplicated, eventhough there is nothing on my external SD card.
That is a good question. One that I don't think anyone has come up with the answer to yet. I was having the same thing happen on ICS. Stock,AOKP,CM10 it didn't matter. The worst part was that I could figure out how it was happening. As soon as you reboot the phone it will add more duplicates. Some weird bug with media scanner would be my guess. So to fix it I deleted all of the .db files from data/data/com.android.providers.media/databases. Then reboot and give the .db time to rebuild. Now never shut down your phone again. llol If someone finds another fix let me know.
I've switched to AOKP JB and have shut my phone off or rebooted a bunch in the past two days and this is not happening. So the other solution may be just to jump on the JB wagon.