Lubuntu Start-up with the Blinds Down

A problem I've found with the current Lubuntu alpha; namely after install and/or tweaking the graphics settings being presented with a black screen or this message:
X-session unable to launch "/usr/bin/start/xde" X-session not found "/usr/bin/start/xde" falling back to default session.
on re-start. A little x-session voodoo?

I got this after installing VirtualBox Guest Additions which reconfigured the display and monitor settings in Lubuntu. I also got this on re-start when I installed Lubuntu on the elderly Compaq laptop...

Why? Lubuntu is looking for an x-session manager that's not installed! It's a dumb default option for an alpha release.

Solved: at your login screen, where the session options at the bottom says:
desktop  Default Default
the first one referes to your desktop session manager, the second to your language choice.

Get the session manager off default onto, say, Lubuntu.
desktop  lubuntu Default
 Everything works fine again. RC