In a continuing effort to provide high quality products, Autodesk has released this hotfix which solves a Vault Add-in for AutoCAD Civil 3D issue where Civil 3D will close with Unhandled Exception on startup if Autodesk Vault 2014 Subscription Release 1 is installed.
The fix had been posted to subcription center. Here is the link: http://subscription.autodesk.com/sp/servlet/download/item?siteID=11564774&id=23295427
Note: This hotfix is only for the users who has installed the Autodesk Vault 2014 Subscription Release 1
and Autodesk Vault 2014 Subscription Release 1 Service Pack 1
Please check README file for additional instructions and description of the issue.