Hi, thanks for your response.
i did not mention vault because I am using data shortcuts, not a project...but you are correct, i am not using Vault. I am running Advanced Road design and the folder protection provided in vault does not sit well with the data sub-folder for ARD.
I did not change the name of the surface, however, there was a couple of times that the surface drawing required audit...it did crash a few times.
Since completing changes to the Area B surface, AND repairing the data shortcut, everytime I open the X_bulk earthworks drawing now, the DS for Area B is always broken.
Thaks for the link, I will try to understand it.
cheers, peter.