I get this error message when trying to upgrade to the latest version of Firefox, Setup has caused and error in SETUP.EXE.
Upgrading from Firefox version 2.0.0.20 to the latest version, 3.6.8. I using Windows ME.
Alla svar (3)
Firefox 2.0.0.20 is the last ever version of Firefox for Win98 / SE / ME. http://www.mozilla.com/en-US/firefox/system-requirements.html
You can try KernelEx to get Firefox 3+ to work, but it would be very slow with an old PC of less than 750Mhz. http://sourceforge.net/projects/kernelex/
Thank you!