Sansa clip+ cannot be mounted in MSC mode

With Ubuntu live cd the drive is recognized.

In fact the drive manager show me this:

internal memory named as /dev/sdc: http://imageshack.us/photo/my-images/813/schermatasandisksansacl.png/

external memory named as /dev/sdd1: http://imageshack.us/photo/my-images/828/schermatasandisksansacl.png/

The difference is that /dev/sdc is not partitioned, but ubuntu mount ti on /media/0123-4567 without problem.

The sd card is well partitioned, the type of the partition is W95 FAT32 (LBA) (0x0C), so the kernel mount it on /media/3437-6235.

If I use fdisk to format the internal memory, after is possible to install the original firmware or rockbox firmware?

Thanks