[lubuntu-users] No desktop appears on reboot of lubuntu 17.10

[Harry Putnam]

Setup:
lubuntu 17.10 as vbox vm guest on Solaris-11 (openindiana) host.
Host harware is HP xw8600 workstation.
Vbox version is 5.2.6

This is a pretty recent install (a few days old) but has been working
normally thru several reboots over a few days.

I did do an update thru the software updater tool during the last
uptime before the recent reboot where this problem showed up.. Not sure
what was installed during the update perhaps it is recorded somewhere?
But more than 1 item was installed.

What I see on a bootup is the appearance of the greeter with login
box.  I then login, after the login is accepted, in a few moments I
see the white cursor arrow appear on a black screen... .. After
waiting a bit I began to realize that the regular desktop was not
going to put in an appearance.

Since then, I've given reboots a nice long wait to make sure my
desktop was, in fact, mia.

So a black screen but no panel or icons, and its not possible to get
any response with mouse

Really had no clue how to debug but guessed it would be one of the
components of the lxde setup.

`aptitude search lxde' showed the meta pkg `lxde' and all the
components as not being installed (because the lubuntu-desktop was
installed at install) I thought maybe if I installed all lxde
components ... whatever was broken might get fixed....  It did not
... still getting the black screen after the greeter login is
accepted.

I'm also running `bionic' (beta lubuntu?) in a vbox vm as well, and so
far this has not happened there.  Though it does make me a bit `gun
shy' about allowing the update software tool to make any updates.