As promised, here is the latest update on the issue where AutoCAD Civil 3D fails to launch after Vault 2014 Subscription Release 1 is installed.
In a continuing effort to provide high quality products, Autodesk has released Autodesk Vault 2014 Subscription Release 1 for Autodesk Vault Workgroup 2014 and Autodesk Vault Professional 2014. Autodesk Vault 2014 Subscription Release 1 focuses on introducing a brand new thin client experience, improving the "Edited out of Turn" workflow, and broadening the feature offerings in the Revit Vault Add-in. Additionally, Autodesk Vault 2014 Subscription Release 1 addresses a variety of issues pertaining to those releases. This README file highlights how to download the Subscription Release, how to install the Subscription Release, and discusses the new features, fixes, and known issues in the Subscription Release.
To summarize it you would need to login to Subscription Center and then visit this link: http://subscription.autodesk.com/sp/servlet/download/item?siteID=11564774&id=22433035
You should get this page:
At the bottom of the page you will see downloads. Go ahead and install it from there.