For older Macs (PPC) that aren't supported in Firefox 4.0+ versions, try TenFourFox. http://www.floodgap.com/software/tenfourfox/ http://tenfourfox.blogspot.com/

Or stay with Firefox 3.6.* where 3.6.24 can be found at http://www.mozilla.org/en-US/firefox/all-older.html

http://www.mozilla.org/en-US/firefox/4.0/system-requirements/

to
http://www.mozilla.org/en-US/firefox/8.0/system-requirements/

Mac Operating Systems

   Mac OS X 10.5
   Mac OS X 10.6

Recommended Hardware

   Macintosh computer with an Intel x86 processor
   512 MB of RAM
   200 MB hard drive space

Firefox 3.6.* and earlier used to come with Intel and PPC versions in download, but now as of Firefox 4.0 and newer (including 8.0) the PPC version was replaced with 64-bit version.

If there are problems with updating or with the permissions then easiest is to download the full version and trash the currently installed version to do a clean install of the new version.

Download a new copy of the Firefox program and save the disk image (dmg) file to the desktop.
You can find the latest Firefox release here:

• Firefox 3.6.x: http://www.mozilla.com/en-US/firefox/all-older.html

• Trash the current Firefox application to do a clean (re-)install
• Install the new version that you have downloaded

Your profile data is stored elsewhere in the Firefox Profile Folder, so you won't lose your bookmarks and other personal data if you uninstall and (re)install Firefox.

• http://kb.mozillazine.org/Profile_folder_-_Firefox