Any news on this? I got the same error message from my win7 pc app... If I try to manually delete songs from the music folder in sd card from my pc, it won't work... It says the device is unaccessible or something. And if I try from xbox music app, then all hell breaks loose and I have to delete songs about 23 times and I only managed to delete songs A to U...
I have tried and tried and I just can't figure this out. The software sees the other two libraries(video and photo), but just can't see my music folder, for some unknown reason. This worked fine for a very long time and I haven't moved my music folder, previous to this problem.
It sucks that someone else has to deal with this, but it's also nice to know it's just not me.