Did you try disabling the "off main thread composition" (OMTC) feature introduced in Firefox 33? The steps are as follows:

(1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful.

(2) In the search box above the list, type or paste layers and pause while the list is filtered

(3) Double-click the layers.offmainthreadcomposition.enabled preference to switch it from true to false

However, I read in a bug report that this causes problems with the HTML5 player on YouTube, if hardware acceleration is disabled, so you might also need to force Flash on YouTube if you keep this setting. You can use an add-on for that: https://addons.mozilla.org/firefox/addon/youtube-flash-video-player/

jscher2000 said

Did you try disabling the "off main thread composition" (OMTC) feature introduced in Firefox 33? The steps are as follows: (1) In a new tab, type or paste about:config in the address bar and press Enter. Click the button promising to be careful. (2) In the search box above the list, type or paste layers and pause while the list is filtered (3) Double-click the layers.offmainthreadcomposition.enabled preference to switch it from true to false However, I read in a bug report that this causes problems with the HTML5 player on YouTube, if hardware acceleration is disabled, so you might also need to force Flash on YouTube if you keep this setting. You can use an add-on for that: https://addons.mozilla.org/firefox/addon/youtube-flash-video-player/

Well I've done as you wrote and now I can only wait and see for the next 24hrs to see if it happens again.

Even if this does work, why have Mozilla not fixed this issue yet?

wyr. said

Even if this does work, why have Mozilla not fixed this issue yet?

Well, like other features that coordinate work between separate processor threads, OMTC is a complex project. I see over forty entries in the bug tracking system for various aspects, refinements, and fixes, many of which are completed, but some of which are still being worked on. Your problem may or may not be fixed in the next release, but let's first see whether a glitch in OMTC is your problem.

Seems to have worked so far.

One OMTC bug affecting users with Nvidia graphics was fixed in today's release of Firefox 38.0.5.

wyr. said

Hi, for the last 6 months or so when I am browsing any webpage whether it be YouTube, eBay or Google, Anything, the screen can suddenly turn black within the firefox browser and as I move my mouse around in the blackness or press Crtl + A to select all it starts to show more of the page that I have selected or moved my mouse over. When I use other browsers such as Opera or Google Chrome I do not get this issue. Firefox has been my main browser for the last 8 years or so ever since I swapped over from IE. This is the first time I've ever been saddened and extremely frustrated with FireFox browser. It seems like its slipping a little and falling behind the others if its been allowed to have this issue for literally months, maybe even a year. Upon reading I found people posting about it in 2014. Firefox support only suggests to 1) Put it in safe mode. 2) disable hardware acceleration. After they do this and reply in the thread saying it still doesn't work FireFox support member stops replying and does not try to help any further. I have already put in safe mode AND disabled hardware acceleration. I've made sure Java, flash, shockwave and everything is fully updated. My graphics card is up to date and the fact no other browsers are doing this. Only FireFox. Hope I'm able to get some help. Would be nice to bring some faith back in FireFox if the issue is actually fixed. Thanks in advance.

I too have the same problem! It jus went black and I cannot even see anything on my firefox browser. I think this is a bug!

Hi mrusli, let's continue in your new question here: https://support.mozilla.org/questions/1095437