Mauro,
I've never had a problem using adir() on FAT16, FAT32, NTFS or Novell. What files systems have you had problems with? It's quite likely a WinAPI call would have the problem too.
>this way I know, but I used this in different types of file system some time ago and I received different results, so I remember that I used a API Function but I don't remember the function, this work's with different types of file system.