Error pop-up won't let me work

I saved a project last night and opened it this morning and went to work. After a few minutes it started giving me an error pop-up saying," Internal data error. Drawing for layer [B_1] was not found. The layer will not be editable.To edit the layer, delete it and create a new one."Unfortunately, it doesn’t refer to a scene # and it kept recurring and wouldn’t let me navigate around to delete [B_1]'s .I had saved a copy to disk that seems to be working ok (knock on wood) for now, but wondered if you might like to look at the problematic project file.

The saved version was screwy too, but I was able to go through it and delete all the [B_1]'s…