What type of Windows 7 do you have? Is it 32-bit or 64-bit? If you have 32-bit, then iRiver Music Manager should work. However, if you have 64-bit,
it will not work, according to a phone call I made to iRiver several months ago.
I had the same problem as you,
and so I called iRiver and that is what they told me,
and then I exchanged my 64-bit computer for a
32-bit computer and now the iRiver Music Manager works.