Here it is… the problem!
I’ve got the 4GB version. I have an old 2GB micro SD that I use on my smartphone. I decided before buying the player to put some music on it and afted going out of the store to put it in the player and to go home… That didn’t happen 
The micro SD was totally formated by the SANSA software. When I got home I put the card in the card reader, formated it again to 2 GB FAT, installer ROCKBOX, put some music using the normal card reader , started the player with ROCKBOX and the microSD. Everything went fine and now I am using both the internal and the external memory.
WARNING!
When charging the player put out the micro SD.
When you hold the HOME button and press the POWER button the ROCKBOX will not start. The buggy Sansa software starts and destroys everything.
I am planning to buy a 32 GB Sandisk micro SDHC. Hope the will be no problems…
