Mustek mp80b to iaudio x5l via usb host port?

All:
I am having some problems trying to get my new Mustek MP80B DVD player
connect to my Iaudio X5L via their respective USB Host ports. The Iaudio
freezes when I press REC in order for it to read the DVD I have in the
Mustek DVD player. I gather that happens either because they are both
USB Hosts and cannot communicate with one another or because they are
both using incompatible signals trying to communicate with one another.
Any suggestions or answers? Any firmware upgrade for the Mustek or
Iaudio that might help in this situation?
Thanks!

Keith