My Memory Stick is defective and corrupts files, that was my problem
Funny it works like a charm in SE W810i or K750i . But when I throw some mp3's or iso's on it while in the PSP it shows 3Mb/s writing speed and from 90 mp3's only 18 worked and not even one iso worked! 10x USB2.0
On good old USB1.1 there's no problem but it's very very slow ;(
10x a lot for the help man!