W810i Failed Playlist
Yesterday, I added a couple 1-hour podcasts to my W810i and dropped them into a playlist. When I tried to play it, it just said "Failed", and shutdown the player. After that I couldn't even open the player with the Walkman button -- it just said "Failed" again and slowly went back to the standby screen.
Restarting didn't help, removing the files didn't help, and removing the card didn't help. Finally, I managed to get into the Walkman player mode through the main menu which doesn't go right to the current playlist. From the Walkman menu, I could select another song and get it playing again.
In the end, I found that selecting the playlist again would cause the failure, so I deleted the playlist and rebuilt it. All is well now. The playlist must have gotten corrupted somehow when I was manipulating it.