Just to let you know that I had the same problem with my Sansa e200 in my Mac OS
X system, which is not a surprise since Mac OS X is built on top of BSD and,
thus, is likely to behave similarly to Linux in this issue.

What is interesting is that if you try to boot the Sansa on Recovery Mode (Power
off, Turn ON "lock/hold" button, Hold down "record" button, Hit Power/Menu
button), when plugged to the MAC through the USB cable, you will see one
additional line (one that doesn't show when you connect it to a PC) that says
"LUN0 locked". This seems suspicious to me... It seems like the device locks
LUN0 on purpose when connected to a non-Windoze system.