Hi

You can try to disable Hardware Acceleration

Firefox tries to use your graphics card to play video, but sometimes it conflicts with the driver.

Goto Menu > Settings > Performance section >

Uncheck the box next to "Use recommended performance settings".

Uncheck the box that says "Use hardware acceleration when available".

Restart Firefox.

or check your Video drivers.

win 10 . runs fine for years now . but now just like garymoir12 above .

i'll be watching videos then they stutter like bad audio track then the video stutters they alternate stuttering by then its too late to end them.

now this happens randomly but its constant . the screen is locked but i can mouse around but not do anything i click random keys on board an i get sounds like i did something wrong ding dong bong so the screen has locked only mouse moves , you cannot reset or send any commands or right cliks the keyboard toggles meaning the computer is running but the screen crashed very nice looking but its same every time . this started with the last update , not the newest , was hoping that the new one had a fix .. not its made my computer useless for videos is there a way to roll back the updates .. i broke my rule to be the last to update ..grrr the system report does say the driver failed for the video an reports it as a AMD driver failure . as for the driver it works in so many other programs an i have many for 3d/animation/editing etc the issue is firefox not my drivers there will be many more reports once they figure where to go. if possible. as i learned in support if there are 2 or 3 reports there are hundreds more likely to follow for me the easiest is to roll back the updates 2 times .