Guilom, this is nothing to do with the firmware so do not try to fix it by changing firmware you will kill your player.
There are no 4GB nano clones they are all fake, the most memory they can support is 2GB. On Samsung chips the 4th and 5th characters of the serial number denote the memory density in your case "8G" or 8 Gigabit which is 1 GigaByte. It has been hacked to read as 4GB. The reason you are having file corruption is because Windows thinks it is 4GB and tries to load files to memory that does not really exist.
You can check it like this:
http://www.mympxplayer.org/feedback-...rs-vt2828.html
To fix the file corruption problem you need to re-partiton the memory and remove the hack. Your chip will then read it's true size of 1GB. "lattesurf" posted a guide on how to do this here:
http://www.mympxplayer.org/how-to-re...ck-vt2400.html
if you look through the forums you will see many posts from members who have purchased hacked Players. There is also the Bad Sellers\Blacklist where members list the sellers that deal in hacked players.
http://www.mympxplayer.org/bad-selle...list-vf15.html