popat007 , you are most definitely scammed. Your player is only a 2GB chip hacked to show 8GB. The problem of the files not showing or having errors are signs that the chip was hacked.
Do not update the firmware, you'll most defintely kill the player.
I'll suggest you contact your seller and either get a partial refund or full refund. And as well sign the petition
http://www.petitiononline.com/eBay666/petition.html