A Design May Not Opened as View Only Because...
You may want to view a design that you do not own. There are a couple instances when this may not be possible. When a design is sent to the field, it is accompanied by an XML packet. This XML packet stores edits made in the field and must be opened in an Edit mode on the Enterprise in order to play the edits back to the geodatabase.
A design with an XML packet cannot be opened as View Only until its owner has opened it and saved the edits to the database. This is also true if your Administrator has decided to create XML packets on all designs, whether they're sent to the field or not. Once the design's owner has opened and saved it, the design can be opened as View Only by any other user on the Enterprise.
No design may be opened as View Only in the field.
In this example, Design 2 is locked because Design 1 has been approved. Note that almost all tools on the toolbar have been disabled. The user may open the design in view-only mode. This user is an Administrator (as well as the Current Owner) and may also delete the Design.
In the event that ArcMap crashes while the user is editing a design, the open design may become locked. To unlock this node, use the Unlock task.