Hello cjones, try to download and run the SearchReset add-on to see if the search preferences revert to default.

if you can not, then if you have an antivirus program check for virus and try also the next free for mac antivirus (as a second option), download with you safari if firefox is unusable : ClamXav - The Free Anti-Virus Solution for Mac OS X

thank you

Current Firefox versions require OS X 10.6 or later, so if you want to continue using Firefox beyond Firefox 16 then you need to update to OS X 10.6.8 or later.

• https://support.mozilla.org/kb/firefox-no-longer-works-mac-os-x-10-5

Firefox 16.0.2 is the last version that works on an Intel Mac with the OS X 10.5 operating system.

• https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/16.0.2/mac/

Another option to consider is to install the last Firefox 10.0.x ESR version as that version is more recent than the Firefox 16.0.2 version.

• https://ftp.mozilla.org/pub/mozilla.org/firefox/releases/10.0.12esr/
• http://www.mozilla.org/en-US/firefox/10.0.12/system-requirements/