Perhaps they could be opened in safe mode in X2a, to see if they opened, then saved off to a new project folder.
IF that worked, perhaps we could collectively try to figure out what is in them that is causing X2a to freak out.
The above is based on a thought that perhaps something with plugins is causing these issues, and by opening in safe mode, all of that could be initially bypassed - to save under new project folders, then plugs could be re-introduced one at a time, until some pattern is discovered as to what is causing the trauma.
Bob Bone