Whenever I try to edit something, my video will randomly get the yellow triangle thing even if no other programs are open (And I never delete or move videos I'm in the middle of working on, as I prefer working start to finish in one sitting), well I used to this at this point so I've started saving my video after I get to certain checkpoints that I set. Well more recently when this happens I'll do my normal close out and open the save I can't edit a thing about the video other than copy and paste and if I do anything else it doesn't do it but instead gets rid of a small portion at the end of the video. So I have to render it and then edit the rendered version. Anyone know how to fix this?