Yep... you were right.
I didn't unmount the Sansa after I transferred the files to it. In Kubuntu, right after doing the e200tool stuff, the Sansa is recognized and opens on the desktop. So, I "dragged and dropped" the new files onto the Sansa. However, I then "exited" the Sansa from linux rather than "unmounted".
Once I got everything loaded, it worked great.
Thanks,
Ray