cory149 Wrote:  Fat with custom firmware or official firmware older than 3.00 doesn't have the lflash sectors crypted, and des cem doesn't use those prx's on a fat (it only loads them if it is a slim).

I confirmed it last night jas0nuk, the 3.80 prx's will cause the same result as using 3.71 ones on 3.80. You can mount it and it won't brick the PSP unless you write to a mounted disk of the wrong format, but it also will not give you a real directory listing either (just garbage entries when you open the disk). No backwards compatibility, in other words.