Share your experience!
I recently bought a second hand pocket vaio and without instructions, have unplug the machine from the computer before clicking on the "unplug software " and have now lost the ability to play any the music, either on the machine or on the sonic stage.
Have you tried resetting the player? (small button on bottom of player)
You may also have to do a format & re-transfer to get your PC & player sync'd properly.
Take a look here for more info
HTH
yes I have reset the machine and as the machine is second hand the music was not from my PC. looks like a lesson learnt.