The following is for the Japanese market only NW-S77x, not for the international NWZ-77x.
It appears there is some kind of bug that makes the song stop at the start of playing. More information regarding the update can be found here but it is in Japanese. But using Google translate should be sufficient in understanding the instructions if you have a NW-S77x.
I personally have noticed a glitch on my NWZ-E575 as well. Sometimes when playing a song for a bit, the Walkman for some reason replays the song from the start. I am not sure if this is related to the firmware or just the cold temperatures we have had in the past few months here in Poland. I haven't had the issue come up in above 0 weather though.
Also I am aware of my late late review of the new E-Series, I promise it is coming soon.