I upgraded U. 9.04 to 9.1 over the net a few days ago and got stung by the 'Driver' issue. Namely, my nvidia card is not reconciled and as a result, the monitor remains blank. I am assuming that the remainder of the upgrade went o.K. though I can only follow the boot sequence on the monitor during the bios start up.
I have a live disk of U. 9.04 and want to revert back to it, preserving my data.
When I put in the disk and am hopefully asked if I want to "Upgrade", will it work in reverse, so to speak. I understand that there is a problem with compatible libraries etc. but will it ignore this and simply replace the new with the old?
Any insights are welcome.
Matthew

It depends on how the "upgrade" is supposed to work, but if it's something like using the disc as a reposity for an upgrade using apt, it's probably not going to work. The quickest and also cleanest way would be to simply reinstall the version you want, overwriting the old operating system in the process. This obviously means that you either need to have backups of your personal data (i.e. home directory or directories) or /home (well, the partition that the precious data is on) mounted on a separate partition from the root partition. If you had a separate /home partition, you would just go through the setup as usual, but select "manual partitioning" and select the home partition to be mounted under /home (without formatting) and root under / (with formatting). Or with backups simply do a clean install and pull the data back. But if you did it the quick way and have everything on a one, big partition, reinstallation might be a problem. Of course you could just select (during the partitioning step) that the partition should not be formatted and proceed that way, but I'd do it the other way.

If you can't boot because your video drivers don't work, you might not need to reinstall anything. Just boot into a maintenance mode or boot from a live-cd and fix the problem, for example (in Xorg configuration file) tell the system not to use the not-working nvidia driver but something else. Once that's done, reboot and start working on it.

Thanks for your input.
I do have my data backed up, last BU about a week ago. I also have the install and the data on one big partition.
I thought I had actually had been booting up and simply couldn't read the monitor up until now. Looking at it more closely, I get all the usual Msgs. from the bios and the moment grub comes up (I can read grub's Msg on the screen, it just announces Grub and v. #) the screen goes dark with flashes of text, which scrolls by forever(too fast to read any of it), suggesting that an OS has not been booted up successfullysuccessfully...or ?
Matthew.