This leaves those of us with old computers which cannot be upgraded to newer operating systems (G4, G5 iMacs, iBooks, eMacs) in a bind. What we see is that every month fewer things work correctly, and there is no official fix.

Fortunately, an organization consisting mostly of people working on the FireFox browser (from Mozilla) and calling themselves TenFourFox (they can't legally use the Mozilla or FireFox names) have adapted the latest release of FireFox to run on 10.4. They also call their browser TenFourFox. Their website on Google Code is:
code.google.com/p/tenfourfox/

There are 4 versions, one optimized for each of the four different underlying processor architectures. You should use the version for the architecture you have. The wrong version may work, but it will work poorly.

Directions for finding which version you should use are at:
code.google.com/p/tenfourfox/wiki/WhichVersion

The download page for the latest stable TenFourFox version appropriate for each processor family is shown in the table below:

Download the zip file for the version of TenFourFox you want and install via the normal installation process.

NOTE:
TenFourFox cannot run simultaneously with FireFox. If you try to do this, TenFourFox will give you a message indicating that it cannot run because FireFox is already running. The cure is to quit FireFox.

- Bob Beeman.