Can you not do that from Options > Advanced > Encryption? Click the View Certificates button. In that window you should be able to read the certificates and remove any that you want removed.

Hmmmm...I saw that, but I can't tell which certificate belongs to the website that I "trusted". Is there a way to figure that out? I guess this is a more complicated question than I originally thought it would be.

Thanks for your quick response!

Go to the site, click the Site Identity Button at the left end of the URL bar, on the Security tab in the now open Page Info window, click View Certificate. On the General and Details tab should be enough information for you to locate the certificate used by the site.

• Site Identity Button:
  • https://support.mozilla.com/en-US/kb/Site+Identity+Button
  • http://www.dria.org/wordpress/archives/2008/05/06/635/

If this reply solves your problem, please click "Solved It" next to this reply when signed-in to the forum.

You can remove the old Java Console extensions that you have installed. You have old versions 6.0.21, 6.0.22, 6.0.23, 6.0.24
Remove them following these instructions: http://kb.mozillazine.org/Java#Multiple_Java_Console_extensions

Ah hah! That worked. I just had to click the "severs" tab, rather than the "authorities" tab, and that was where it was located. Thank you so much!