After some more testing the bottom line is that a game ran from the internal HDD just freezes ( whenever it wants ) or give s Unreadable disk.
Unitl now I've tried these methods, all returned Unreadable Disk at some point or the game freezes:
- Install from DVD to HDD, and then use NXE2GOD
- Use ISO2GOD to extract an ISO, and then copy it trough ftp ( XexMenu )
- Install from DVD to HDD, and play with the DVD inside
- Extract an ISO with another program ( forgot the name

), somewhere on the HDD, and the result is the same
Playing the game form the DVD ( without installing ) gives no errors

Harddrive works fine ( got it from another jtagged console )
As stated above, a console with the same specifications ( 512MB jasper, XBR3_BB, almost same mfr date ) has the exact same problem, so the obvious problem is the XBR3 dash.
That only means that the solution is XBR4, but if there is other it will be great
