I received a drawing which had a digital signature, and I get a ".dwg is currently in use or is read-only" upon opening. I saved a copy of this drawing with a new name and made a bunch of changes, added layers etc.
When I open this drawing now, I don't get any of the messages I mentioned (read-only, signed), and everything I have done in paper space remains as it was before I closed it. However, all of the model space data is missing, gone. If I copy objects from the original version into my new saved version, it comes in just fine. I've tried opening with Civil, regular CAD, restarted my computer... nothing seems to work.