OpenLayers map does not display after Firefox update


I have a problem with displaying the openlayers map.
The map was working fine for a long time, but a few days ago the map just dissappeared. I checked the map’s visibility on different OS(Windows 7, 8, Ubuntu, FreeBSD) with different browsers(Firefox 2X, Opera, Safari) and we got mixed results. At the end the conclusion was that after the Firefox update (from 2X to 23) the map dissappeared. Can firefox update cause this?
I deleted the browser’s history, the cached web content and the browser’s cache folder as well. Nothing happened, the map still does not display.

Any ideas?

I downgraded firefox from 23 to 20 and the map started to display. On firefox 21 openlayers map works as well.

I found an other solution, which temporarly solved the problem. From ff 23 this worked:

Probably the causer of the problem is the Mixed Content Blocker, in Firefox 23.