AdBlockPlus problem solved Rated 5 out of 5 stars
To Wladimir Palant,
The problem was the StartCom Certification Authority settings, as you suggested. The “This certificate can identify software makers” option was UNCHECKED. After checking it and saving, I was able to load your AdBlockPlus Firefox addon.
Thank you very, very much for responding. I would likely have never found this on my own. It is people like you who make FOSS so much better.