This may help others:
I had a problem when upgrading from Ubuntu 9.04 to 9.10 in that the fstab could not be mounted. The way I solved it was to do the following.
I hit "ESC" and it popped me into a shell. You then remount your filesystem like this:
Code:
mount -o remount,rw /
Then you run the following
Code:
sudo dpkg --configure -a
Once that completes, you reboot.
It worked for me :-)