Transfer of the newer document (actually, any document) by scp to the documents folder **might not** trigger the firmware to re-scan the documents folder (causing what appears to be a display lock-up).
core2quad kual-v.0.3.2 $ scp KindleLauncher-2.0.azw2 kpw:/mnt/us/documents
KindleLauncher-2.0.azw2 100% 84KB 84.0KB/s 00:00
Force a re-scan of the documents folder by:
core2quad kual-v.0.3.2 $ ssh kpw "dbus-send --system /default com.lab126.powerd.resuming int32:1"
This problem can happen with firmware as recent as 5.3.3 (Kpw).