Virtualbox guest additions kill X in Ubuntu

[Graham Watkins]

Good day to you.

I had Ubuntu 12.04 installed in Virtualbox which ran OK, if a bit slow, 
until recently when I did a bunch of updates.  As is usually the case 
after kernel updates,  I had to reinstall the guest additions to get 
back full screen and auto-resize.   However, what I got instead when I 
restarted, was the following message:

"The system is running in low graphics mode
Your screen, graphics card and input device settings could not be 
detected correctly.  You will need to configure these yourself"

It then drops into a menu with buttons where most of the options don't 
seem to work and eventually bring me to a command line login.
I've tried a complete reinstall followed by an upgrade to 12.10 but 
again the installation of guest additions bring me to the same point
If the graphics settings can be configured I'll need some advice on how 
to go about it

I don't think I can provide log output as cutting/pasting between guest 
and host no longer functions.

This is Virtualbox 4.2.12.  The kernel is 3.2.0-43-generic-pae i686

Cheers,

Graham Watkins