Unreal closes after few adjustments

I’m really new using Unreal, I’m trying to make a previz, so I have a bunch of sequences with mocap performances, I started to have problems every time I make an adjustment inside of a sequence, the program crash, I try to move all the elements to a new project but the problem persists after a few adjustments inside a sequence, the program crashes again. I detect in the outliner of every sequence there is ghost text of “Deleted Actor” I don’t know if this could be the problem but there are a lot of them in every sequence.