This can be caused by "anti-exploit" or similar software killing or freezing the child processes of the main Firefox process. They want to inject code into firefox.exe and Firefox doesn't want them to. But this is not a new problem in Firefox 75, so I wonder whether something might have changed which suddenly now makes it a problem?

nothing much. I using windows 10 on my laptop and only using windows defender. In April, I only received windows defender definitions I don't remember I've installed anything lately. I'll try running malwarebytes

do you happen to have "netsupport school" software installed on the affected device?

@philipp_> no I don't malwareytes scanned the system and found nothing

ok, that would be a legitimate 3rd party software though and something that gets picked up by malwarebytes.

i was asking because we have seen similar reports from users with that tool installed. mozilla developers are working on a mitigation against that: https://bugzilla.mozilla.org/show_bug.cgi?id=1629361

I've attached an animated gif depicting the behavior of Firefox. Please let me know if you need any extra information

hi again, 76.0b5 was just released and has a potential fix for this - could you try it?: https://www.mozilla.org/firefox/all/#product-desktop-beta

on the first start it will likely exhibit the same problem, but after you force-close it once and restart the beta build, firefox should hopefully be back in working order.

I've installed 76.0b5 but issue was not resolve

does that stay the same after you reboot your system once?

yes, it's persistent

Hello, Try following steps :

1) Restart your computer.

2) Clear your cookies and cache.

3) Restart Firefox in Safe Mode.

4) Reinstall Firefox.

5) Refresh Firefox.

6) Create a new Firefox profile.

7) Other solutions. Check browser internals. Troubleshoot the Flash plugin. Check for conflicts with your Internet security software. Check for malware.

Devinda, I've previously done almost every point you mentioned with no luck. Nevertheless, Just now I tried opening Firefox, and to my surprise it worked fine. I don't remember doing ANYTHING in particular other than uninstalling some steam games which has absolutely nothing to do Firefox