I'm in contact with iriver's support group and we ran through most of the suggestions mentioned here.
They suggest that a powered USB hub may be necessary so I'll beg, steal, buy or borrow one and get back to you.
This is guy I'm talking to, surprisingly enough he's in Melbourne.
wlim@crkennedy.com.au
MacE, I did a greenapple suggested and got "new hardware" noises but no new USB drive shows up on My computer.