I stole this wording/reply from my buddy @Darin.Green, so he takes all the credit for the steps..
This should help get your application working. Assuming you have a valid serial number/contract.
Close the application
Please note, folders of C:\Programdata and C:\Users\[Username]\Appdata (listed below) are hidden folders and you may need to adjust your viewing settings.
On your computer, navigate to: C:\ProgramData\Autodesk\CLM\LGS\<Product_Key>_20
Delete the LGS.data file.
Navigate to C:\Users\[username]\AppData\Roaming\Autodesk\ folder
Delete the ADUT folder and it's contents
Start the application.
When you start the application, it will prompt you to choose one of the following:
Login - 30 day trial licenses
Serial Number - Standalone and Single-User activation
Network - Network License server for obtaining licenses from a machine on your network
Choose the option that matches your license. Students will always select serial #.
, Certified Professional in Autodesk Inventor 2014/2015/Exam & AutoCAD 2014 and not an Autodesk Employee
Installation | Autodesk Virtual Agent | Autodesk Register Once | Activation/Chat | Microsoft Fixit | Desktop Sub-Grant User Access | Error 1603 | Autodesk Med Resolu Libray | Inventor Reset | Screencast
Kudos is much appreciated if the information I have shared is helpful to you and/or others
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