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Firefox is not displaying alt codes correctly, substituting a black diamond with a white question mark in their place.


Alt codes (such as ® for "registered" and ™ for "trademark") are being displayed as a small black diamond with a white question mark inside of it. This has also started happening to more simple characters such as exclamation marks, dashes and apostrophes. Any ideas?

Additional System Details

This happened

Every time Firefox opened

This started when...

April 8, 2011

Installed Plug-ins

  • Adobe PDF Plug-In For Firefox and Netscape 10.0.1
  • The QuickTime Plugin allows you to view a wide variety of multimedia content in Web pages. For more information, visit the QuickTime Web site.
  • Shockwave Flash 10.2 r153
  • iTunes Detector Plug-in
  • Google Update


  • User Agent: Mozilla/5.0 (Windows NT 6.1; rv:2.0) Gecko/20100101 Firefox/4.0

More Information

I can change these back using the same alt codes in an HTML editor, and they then display correctly.

  • Top 10 Contributor
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10738 solutions 96624 answers

Helpful Reply

Does that also happens with those characters in your above post?

Make sure that the correct encoding (View > Character Encoding) is selected.

Press F10 or press and hold the Alt key down to bring up the "Menu Bar" temporarily.

Helpful Reply

Thanks for your reply cor-el.

My posting actually included the alt code syntax, and is now rendered as the corresponding special character. I guess this isn't a surprise!

And no, it was rendered just fine. This morning when I went into the browser to see the problem, it was not mis-displaying as it had been...it had somehow changed and was behaving very nicely. That's all fine, but I'm a little bit wary of this FF browser functionality now...steady as she goes.

Also, I did check the (View > Character Encoding) you recommended, and after experimenting a bit discovered that using "Unicode (UTF-8)" made the wierd black diamond/white question mark character come back in all of the same places it was occuring...up until this morning. I've set my browser default to "Western (ISO-8859-1)" now, and everything is displaying as it should.

Thanks for your reply and suggestions. I hope others will learn from these experiences.