I have spent literally hundreds of hours over the past year and a half or so trying to figure out why Firefox and Adobe FlashPlayer cannot coexist peacefully. The latest issue that I have found has to do with Firefox refusing or unable to use the "sandbox" technology that every other browser apparently uses. I occasionally use Google's Chrome browser and have begun exploring Microsoft's new Edge since I updated my OS to Win10 about a week ago. Neither platform has any problem whatsoever with Adobe FlashPlayer content. I have been a very dedicated and contented FireFox user for at least the past five years except for this problem which has become unendurable since my Win10 “upgrade.” With Win8.1, I completely booted all traces of Adobe FlashPlayer off my computer and simply ignored content that depended on it. This does not seem to work since my “upgrade.” Now, every single site I access that has any Adobe Flash dependent content in it brings my entire FireFox browser to a screeching halt for approximately a minute. I frequently end up using the old three finger salute to end the grid block that has become standard operating procedure with my current use of FireFox. I am brought to a point where I have to consider abandoning FireFox completely until this “disconnect” is at last addressed and permanently resolved by Mozilla FireFox. I have tried all the "safe mode" fixes. I have updated every updateable parameter imaginable. I appeal to anyone in the community who has a workable fix for this problem as a last resort before I move my online activities to another browser. I will respond quickly to anyone who offers help and needs me to try something to fix this. Thank you for any assistance with this longtime problem.