Screen shot of the error?

Do you mean the error described in this article:

What do the security warning codes mean?

The error page usually has an "Advanced" button. If you click that, additional information is listed including a code that usually starts with SEC_ERROR. Could you copy/paste that section into a reply here?

And to jump ahead a little, this article describes some reasons you might get this common error code:

How to troubleshoot security error codes on secure websites

Does that help?

It won't let me take a screenshot. It says it isn't a web page.

Error code: SEC_ERROR_UNKNOWN_ISSUER

I just looked at the data you shared (next to your post, Question Details > More System Details) and it shows a disabled Covenant Eyes add-on.

Even if the add-on is disabled, the way Covenant Eyes works could involve intercepting your secure connections. That would be similar to the security programs listed in the article I mentioned before.

Yes, that does help. Thank you.

If the above meas that it Solved the issue could please Mark this as Solved with the Solution so others can find it.