When I use Firefox to view web pages that include Apple Maps, this sends my monitor to sleep (simple message "Attention Entering Sleep mode" then screen goes black). There seems no way out of this except to switch off the PC and reboot. This only happens in normal mode, web pages display normally in Safe Mode. Tried Refreshing Firefox, disabling all Plugins, disabling hardware acceleration; I have no Themes or Extensions; new Profile - none make any difference. When the map starts to load, it gets to the point where text (i.e. place names) are rendered but the text is garbled and then the monitor goes to sleep. Any ideas anything else I can try? Can I somehow debug the rendering of the map? Or am I resigned to always using Firefox in Safe Mode - does this matter anyway? Thanking you for any suggestions.