alright so i had this issue a little while ago, and for some reason the ticket i made simply vanished 
so i thought i would ask here anyway having firefox in a sandbox causes a bluescreen when trying to save to other drives i have tried the avast 7 beta and it was still an issue on that one so i went back to 6. since i am pretty bad at describing things here is a video of the issue
I can’t get the video to play, the timeline just disappears and the ‘play’ button greys out.
i checked it and its working for me? (redownloaded it and it played)