Unfortunately, Firefox 4 supports only Mac OS X 10.5 and above on Intel hardware. The system that you are currently using is no longer supported by Firefox (details can be found here).

You should revert back to previous version (3.6.16) of Firefox by following these steps:

1. Open the Applications folder.
2. Drag the Firefox application to the Trash.
3. Download and install Firefox 3.6 from here.

THANK YOU, DYNAMITE! It works beautifully now.

Anne

I have Firefox 3.6.6, and now that Firefox 4.0 is available, it crashes constantly. Sometimes less than 5 minutes after I open it. I have a Mac 10.4.11, so Firefox 4.0 isn't an option for me. When I asked Ff to check my plug-ins it said there was an error and to check back later. Twice.

Because I didn't have any (any) problems with my Ff before the upgrade became available, I am forced to question if Ff has done something to make the earlier version crash so you'll upgrade, but I can't afford to upgrade my Mac right now.

In the meantime, I do need a browser that works! I dislike Safari, Chrome is also not available on Mac 10.4.11, and Explorer is just plain not available on Mac.

Do you have any suggestions on how to fix my Firefox 3.6.6?

Ty

@Inzd, Firefox has done nothing to cause crashes in previous versions. Most probably, it is due to an add-on.
Please check if the solutions given in this article help: Troubleshoot Firefox crashes (closing or quitting unexpectedly).

As an alternative, you can install another browser called TenFourFox from here since it works on Mac 10.4: http://www.floodgap.com/software/tenfourfox.