This is most likely caused by '''The Browser Highlighter''' add-on. Uninstall or disable this add-on from Tools -> Add-ons -> Extensions. You could also try finding an update for this extension. See [[Uninstalling Extensions]] and https://support.mozilla.com/en-US/questions/682558 If that does not solve the problem: Go to the address '''about:crashes''' and tell us your latest crash IDs. We can then look at the data specific to your crash and have a better idea of what is causing the problem.