Well that error means for some reason the routine that finds out which drive letter the sony reader is mounted on, is failing. It works for me, so in order to debug it, you're going to have to do a little work.
First, install python 2.5 from python.org
then install the following two packages
https://sourceforge.net/projects/pywin32/
then
http://tgolden.sc.sabren.com/python/wmi.html
Then open a terminal and start the python interpreter which should be something like
c:\Python25\python.exe
At the interpreter prompt type or paste the following commands
Code:
import wmi
c = wmi.WMI()
drives = c.Win32_DiskDrive()
ids = [d.PNPDeviceID for d in drives]
print ids
Post the output of the print command. Do this with the reader connected.