AutoCAD 2013 hangs at a percentage when opening a drawing. If left long enough, AutoCAD will launch and open the drawing.
As a temporary workaround and to speed up the opening process, copy the file to the local machine and disable the network adapter.
The issue can be caused by embedded objects located on a network file share that is no longer accessible.
To resolve, within the drawing at the command prompt type XREF to list all embedded objects.
Verify that all objects listed are valid and accessible and remove obsolete items via right click - Detach.