There is no "undo" for Firefox updates, you would need to download the previous version you were using, uninstall the current version, and then re-install the previous version that you had.

What particular issues for you have with Firefox 8.0.1? It might be easier for you to fix what you see wrong than go back to the earlier version, which might not be supported any longer or not have the security updates that are in the two currently supported versions - 8.0.1 and 3.6.24.

8.01 forces me to use tabs, which I hate (I can see no option to disable tabs) and broke many of my add-ons. It also made icons in my bookmarks look like hollow squares. I have no idea of what else is screwed up but I am not going to continue using it. I want my previous version back but they have not made it easy to change back. I hate this new version. I am not even sure of which previous version I was using before this wretched update.

Has anyone address the failure of Firefox to even start when the latest version of Roboform is present on the computer ? Ever since the update to 8.0.x, I have had to switch to Chrome in order to access the web. Right now Firefox is useless.

I've removed both Roboform and Firefox, but even leaving any remnants of either causes Firefox to crash. I was able to reinstall Firefox without Roboform being installed and it started up.