Can you describe the problem in more detail? Some issues are very easy to fix.

Due to security vulnerabilities, using Firefox 4.0.1 is not recommended. Firefox 3.6.18 would be the safer choice if you want to roll back to an earlier version.

Can you please tell me how to go about downloading firefox 3.6.18 Thank Orville.

(I don't understand the image. ???)

Here's the process to roll back:

First, I recommend backing up your Firefox settings in case something goes wrong. See Backing up your information. (You can copy your entire Firefox profile folder somewhere outside of the Mozilla folder.)

Next, download and save Firefox 3.6 to your desktop for future installation. http://www.mozilla.com/firefox/all-older

Close Firefox 5.

You could install Firefox 3.6 over it (many have reported success) or you could uninstall Firefox first. If you uninstall, do not remove your personal data and settings, just the program.

Unless you have installed an incompatible add-on, Firefox 3.6 should pick up where you left off. If there are serious issues, please post back with details.

Note: I haven't actually tried this myself!