Problem solved on a mp4 player looking like this one :
I brought it on ebay, as a 16 GB... there's a sticker : 16 gb !
In fact, it's a 2 GB , only the sticker is 16 Gb !
Firmware : QS_AK2025C
2008/04/23
9.5.54
Chip on it is a K9GAG08U0M, so, 2 GB
I've solved the disk error problem using :
first, Fat32Formatter (
download here) simple utility (one file, no install), and making a 1950 Mo partition. As fat 32Formatter is unable to format it, probably due to the hacked system, then, simply format the drive with windows.
Hope it helps.