Before upgrading to 12.04, I completely backed up 11.10 oneiric with deja-dup. In 12.04 I had major nvidia-related problems, so I decided to roll back to 11.10.
I tried to restore from the backup and at first failed several times with "an uknown error occured". I reformated my hard drive, installed a fresh copy of 11.10 on the hard drive, and tried the restore again, with no success.
I then booted from a live usb and ran the restore again after mounting the file system. I chose the restore location to be "file system" and the restore completed successfully, or so it said.
After restarting my PC, all I got was a 'no operating system' error. I remounted my partition chrooted and installed the kernel.
I am working now but my question concerns the restore. Why didn't the restore worked? I'm hoping someone has thought of something that I have not.