This problem occurs when external references (Xref) are used and its re-occurrence can be erratic.
It could happen even after opening and saving the drawing several times.
It relates to all OLE objects that can be inserted (images, Excel spreadsheets, Word documents etc.).
If you have this problem, you just need to delete the .vbi extension file with the same name of your drawing found in the same directory as the .dwg file.
