I perfomred a clean uninstall of both AutoCAD Mechanical 2013 and Vault Pro 2013 and reinstalled both and my user is still getting the error.
I did a clean uninstall of Microsoft.NET4 and reinstalled it and my user is still having this problem.
The problem is machine specific because the user gets the error under his login and I also get the error when logged into my admin account.
AutoCAD Mechanical 2013 opens local AutoCAD files by double clicking on them in explorer and by open them from within AutoCAD Mech. This problem only occurs when opening AutoCAD files from the Vault Explorer.
John C Weiss Jr. CAD Administrator Follett Corporation