Sooo many posts here on this *same* issue over sooo many years for so many versions and *nobody* in any post I can find has a fix or functional workaround. Well, this worked for me and if your computer has more than one CPU (ie. hyperthreading, dual core, quad core, Icore, etc.) then this should work for you too. At the very least, it should help prevent the need to cold boot to reclaim your PC.
It occured to me ... my PC has more than one processor so if I can just keep one of them alive when Flash Player randomly decides it time to fully lock up the whole PC then at least I will not have to cold boot to reclaim my PC. Sounds like a great idea, right? Well, first I had to run a search to see if I could find a utility to manage processsor assignment for specific programs, like "my browser". I found a small selection of free utilities. One in partitular from a reputable source that seems to do the trick. Its from Tom's Hardware and was actually written by their programmer (Daniel Schuhmann) so you know its "clean":
Should read the full Article:
The download link they provide there is broken and they seem unwilling to fix it but this is a working link also direct from Tom's Hardware:
THE REALLY GREAT NEWS:
I don't know why but it seems simply forbidding Flash Player from using all the processors put an end to the lockups. Watched lots of Flash videos since I started using the affinity manager and not a single freeze since. I cannot call it a 'fix' but it seems to be a functional workaround.
Now, in my case, I only want to be sure flash cannot freeze me out of every resource and *FORCE* me to do a cold boot, so I used the process affinity manager to limit my browser to 3 processors
[ ] CPU 0
[x] CPU 1
[x] CPU 2
[x] CPU 3
If your PC has an older processor you may only show 2 CPUs when you run the utility, in which case you could try cutting out just one of the two:
[ ] CPU 0
[x] CPU 1
If your PC is really old you may see only one CPU afailable when you run the utility, in which case you are SOL.
NOTE: You must have the utility running *before* you open your browser, and you must leave it running while you browser and watch vids. Unfortunately they did not give us a 'Minimize' button so I just launch it, push it off the edge of the screen and then open my browser. Other *FREE* CPU affinity managers are available but I selected this one because it has the smallest footprint (low resource demands) and all the control I need.
BTW: I have not noticed any speed reduction or performance cut of any kind by limiting CPU affinity on my browser. I have not tested bu I suspect I could cut down to only one or two CPUs and not see any cut in performance. Let us know is you play with it further than I did. I have my workaround, I shared it here and now, I'm done