After saving a projecct containing numerious scenes I saved .dvc file as normal.
The next time I tried to open DVC3 crashed while trying to open the file.
Started the project again saved as a different filename.dvc.
Again DVC3 crashes while opening this new file.
Tried again with a very simple file and DVC is OK.
This must be a bug with DVC3 that cannot open the data file that DVC3 saved.
OS-Win7 64bit