I have Firefox Dev edition.
I also have a Speed Dial application.
When I load FireFox, the speed dial shows as desired. When I click on any web page, all I see is a black screen.
I disabled hardware rendering. The same issue persists.
Unlike this question Pages appearing in black on Firefox Developer Edition , I am not using a VM and the issue occurs on my home PC and work PC. They do not share any apps or sync.