Help with lost GUI in Ubuntu 11.10

[Peter Hillier-Brook]

I recently lost the GUI after an update, apparently related to missing 
nvidia support in the kernel. Does this ring any bells and, if so has 
anyone any helpful suggestions?

For information, I boot from a disk holding GRUB and Kubuntu which works 
fine, but a second disk with Ubuntu is the failing one. Both systems are 
updated daily and are in sync with each other as far as common files are 
concerned, although I rely on osprober on the Kubuntu disk to find 
Ubuntu, rather than chain-loading. Naturally I run update-grub on the 
Kubuntu disk after any changes to the Ubuntu system and this environment 
has been error free until Ubuntu was upgraded to kernel 3.0.0-15-generic.

Thanks for any suggestions.

Peter HB