You may have a conflict with another application while running FireFox, but you can still correct it.
- Uninstall FireFox and reboot your system
- Install FireFox and do Custom installation (you should NEVER EVER do any installation other than Custom on ANY piece of software, but this is my opinion).
- When the software installs, it will ask you about two FireFox features. One is already marked. Make sure BOTH are UNMARKED. This way, the chance of extra process working in the background on your machine, will crapped out and stop FireFox.
- After unchecking the two options, allow the installation to complete.
- You should not get the error message again.
PCBWizz