Firefox 4 requires at least OS X 10.5 and an Intel Mac.

• http://www.mozilla.com/firefox/4.0/system-requirements/

For Mac OS X 10.4.11 or Mac OS X 10.5.8 you can look at:

• http://www.floodgap.com/software/tenfourfox/

Firefox 3.6.x can be found here:

• http://www.mozilla.com/en-US/firefox/all-older.html

Thanks. The URL for 3.6 was what I needed.

This oversight is inexcusable!! I am also running 10.4.11 on a PowerPC Mac, and I received a notification advising me to update to Firefox 4.0. I checked first, and not only was there no warning that it was compatible only with Intel computers running 10.5 or higher, but it showed that it required 10.4 or higher! Mysteriously, this is gone now.

I lost everything, and now have nothing to lose by going back to Safari. You (Mozilla) axxholes have cost me a lot of time!!!

It would have been so simple to put "system requirements" prominently on the download website!!! Instead I was notified to download 4.0, did so, it replaced 3.6 on my applications and then, of course, is inoperable! I run Mac OS 10.5.8 on a PowerPC Mac--you need to make 4.0 compatible with that operating system--PLEASE!!!!

mjrucker,
That ain't gonna happen. Use the version of 4.0 that was created by other Mac users.

TenFourFox for PowerPC's running Mac 10.4.11 & 10.5.8 .
http://www.floodgap.com/software/tenfourfox/

Thanks for the link. When I clicked the English US version which indicated a 3.6.16 download, it began downloading your version 4.x, which definitely does not run on a PowerPC mac running 10.5.x.

 What is peculiar about the entire episode is that the second time I performed the exact same clicks and selections, and it did download version 3.6.16.   Was that just a glitch in your system?  Or was something fixed?

Is your link broken, or are you attempting to force people over to another browser?

I found TenFourFox a little buggy. I did like using it but it's got problems. hope they fine tune it soon. I really like how it handles speed wise.