looks like you are yet another victim of mp4 player memory hack
see the following article on how to check and repair (please do not repair if you are to open a dispute with paypal against the seller though)
http://www.mympxplayer.org/how-to-re...ck-vt2400.html
also, get your ebay sellers names and search this site with them, you may find them on the blacklist of bad sellers.
this is a massive problem and many, including myself, have been caught out by this, basically it may mean that what you actually have, regardless of what the players or your seller says, is actually only 1GB memory
in short you may have been conned and looking at the link you provided you most definitely have as you will not get a 4GB player for that price anywhere
sorry for the possible bad news but you could always start a dispute and get your money back