Error occurred during a cryptographic operation.

Hi,

I have a similar issue to: https://social.msdn.microsoft.com/Forums/security/en-US/f7cf5c3d-c190-4fa1-90d8-25b9b2694df1/error-occurred-during-a-cryptographic-operation-machinekeyunprotect?forum=WindowsAzureAD 

I have an app under development which uses the Azure AD (which isn't local) for authentication.  It has always worked without any problem, but when I hit F5 and run it in debug from visual studio I now get the error of 

Error occurred during a cryptographic operation.

Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code. 

Exception Details: System.Security.Cryptography.CryptographicException: Error occurred during a cryptographic operation.

Source Error: 

this.Deserialize((Cache == null) ? null : MachineKey.Unprotect(Cache.cacheBits,"ADALCache"));

Apart from some updates being applied to visual studio, nothing else should have changed.  I have tried doing a repair on visual studio, IIS express but no difference.  Cleaning my browser cache and no change.

This is now a major issue, please could you advise?

Thanks