the dev files in this package are for the jreceiver rio client. basically what you do to use the jrec rio is untar the receiver.arf (from rio), delete the contents of the dev folder and unzip the rioboot dev.zip into the dev folder. when i do this, it works. when i delete the contents of the default folder and untar the rioplay receiver.arf file, the nfs log gets stuck on the dev folder contents.
Again, I have no idea exactly what either the RioBoot or the tar utility are doing, but here's my guess at the problem: Windows has no concept of the "special" files contained in the /dev directory. I looked at the dev.tar file, and it contains the same dev entries, but with odd looking properties. My guess is that RioBoot is seeing these special Windows versions of the /dev files and sending the correct information to the Rio instead.
Anyway, try this (if you haven't already): untar the rioplay receiver.arf, delete the contents of the dev folder and unzip the rioboot dev.tar file into the dev folder.