We have a 2008 drawing that contains 8 or so xref overlays. Some of these xrefs have attached xrefs and most have at least one xref overlay. After creating a viewport in paperspace, the viewport scale was changed to 1" = 10'. It worked fine. Then the annotation scale dropdown was selected so that it could also be changed to 1" = 10'. That's when Civil 3D 2008 froze. The only solution was to kill the AutoCAD process tree.
The workaround is:
- Unload all xrefs.
- Change the annotation scale.
- Reload all required xrefs.
The long-term solution is to open all xref drawings and audit, purge reg apps, reset scale list, and detach missing xrefs. Most of this process can be achieved relatively quickly through two utilities released by Autodesk this year.