Hello there,

This could be cause by a corrupt add-on in your browser.

In order to troubleshoot this we'll need you to disable all your add-ons/extensions by going to:

1. Click on the "Menu" button on Firefox 2. Click on "Add-ons" 3. Click the "Disable" button on the side of each add-on

You can then relaunch Firefox and see if the issue still persists.

Helpful topic: https://support.mozilla.org/en-US/questions/1035523

Hope this helps!

The McAfee SiteAdvisor extension has been reported to cause issues with text Chinese (CJK) characters appearing on tabs, so you can disable this extension until McAfee releases an update to address this issue.

• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

• How to uninstall SiteAdvisor:
  http://service.mcafee.com/faqdocument.aspx?id=TS100162
• Strange characters (appears Chinese or Japanese:
  https://community.mcafee.com/thread/76071

See also these threads:

• [/questions/1034427]
• [/questions/1027393]