I don't know if the clips are too big or if it is because I'm around 20 minutes long...but I'm trying to cut one of the files to edit and make transitions but as soon as I do it, all files after minute 4 erase and I have to UNDO and then it's the same thing over and over.

But it does allow me to erase a file completely...what can I do? This has only happened to me today...is there something going on?