Gerome, It sounds like you have a hacked player and the chip is only 512MB. The reason you can not recover the 4GB is because it was never really there. You will find heaps of posts from othewrs with this problem in the forums. I suggest you open the player and check the serial number of the largest chip on the board with this list
http://www.mympxplayer.org/samsung-a...rs-vt1692.html
There is nothing you can do for this, if you used eBay and PayPal to purchase your player there is an article that explains what you should do to report the matter and get a refund.
http://www.mympxplayer.org/hacked-pl...ay-vt1883.html