I don't know much ,if anything , about what I am about to type , and I have been drinking , so be warned that it is purely guess work.
I wonder if the
boot sector or the
Master Boot Record on the hard drive is not compatible with the iriver's bios/firmware ??
I've only ever tinkered (unsuccessfully) with it on a old hard drive and some freeware programs.
There are a few freeware programs if you google
free mbr repair but no doubt it would void any warranty you may have.
Any way its just a wild guess ......