I received email from my dealer when I had a bit of trouble with my Serenata, and it said the following;
"When you transfer music to Serenata from a MAC computer, remember to 'eject' Serenata properly from the
computer (by means of the 'eject' function) before you disconnect it from the MAC, otherwise the Serenata
memory may be corrupted and the storage must be re-formatted and all the music must be transferred
again. "
I had a problem similar to yours, and when we tried it on a PC in the B&O store the dealer and I had no luck in getting music on. Therefore it was a problem with the phone. Pulling the lead out without ejecting the drive will not work, and may even be the cause of the problem as you could have corrupted the memory. My advice would be to take it to your dealer and explain the problem, He'll get in touch with the technical dept at B&O who should send him a list of number sequences which can reformat the hard drive. If that, like in my case, fails to work, I'm sure there'll be no problems having your Serenata replaced for a functioning one. This is what happened to me.