https URLs with mixed content cannot be displayed

[SebastianA]

Hi, I cannot open this page:
https://blog.getfirebug.com/2012/09/03/firebug-1-10-3/
with Firefox 15.0 and NoScript 2.5.4. If I use the same Firefox install (15.0) with a different profile running NoScript 2.3.9, I can open the page fine, having dismissed a pop-up Firefox warning about the insecure content. What I get instead on 2.5.4 is:

This Connection is Untrusted

You have asked Firefox to connect
securely to blog.getfirebug.com, but we can't confirm that your connection is secure.
Normally, when you try to connect securely,
sites will present trusted identification to prove that you are
going to the right place. However, this site's identity can't be verified.

What Should I Do?

If you usually connect to
this site without problems, this error could mean that someone is
trying to impersonate the site, and you shouldn't continue.

NOTE: There is no option to continue. Only to 'get me out of here' or to view 'technical details'.

[Giorgio Maone]

It works for me .
Did you actually try to disable NoScript and see whether the problem actually persists?

[SebastianA]

Hmm... my apologies! I have the same problem with NoScript disabled (now on 15.0.1), so it can't be a NoScript issue. Very weird though - as it works fine on another Firefox profile on the same computer (that had an old version of NoScript installed). I never had this kind of issue before the upgrade to 15.0 - if Firefox decided to display the Untrusted Connection page, I could always add an exception before. Now that option is not available. And on the other profile it does not even display the Untrusted Connection page - it displays a pop-up warning about the page containing insecure content. Do you have any idea how I can resolve this (without losing settings)?

[SebastianA]

I can still not display the page with all add-ons disabled (in safe mode). Alternatives to pressing the Reset button?