Ok I have a healthy Feisty install.
On one of them umpteen logins noticed an upgrade button in the updates window. Well what could go wrong. Right? Extemely WRONG 
Things went good during the upgrade. I rebooted.
At that point it croaked with a greeter app crash error
Well took a month to get back to the issue.
All I did was get into maintenance mode (“Boot to hard disk” –>”recovery mode” entry from GRUB). and type these on screen at the prompt(sequentially after each finishes…each take a few mins to complete)
a) refresh apt's cache
sudo aptitude update
b) run the upgrade
sudo aptitude upgrade
c) GNOME is all screwed up…so run this too
sudo aptitude install xorg gnome
Well that did it!
Now have Gutsy. When Hardy comes out I will have the once-bitten-syndrome 
