I've got one of my users who is still using 2018 SP3 free (we're still waiting for the budget approval for the paid version) that can't use the program anymore, whenever he tries to start it, you see the splash screen and then the program windows opens up for a fraction of a second and is closed, no error message... 

i've tried reinstalling and it doesn't even get the activation request pop-up window, still the same thing.

If i use another profile on that computer, it will work without any problem.

i've deleted the registry dassault and activation keys, deleted the roaming folders without any change.i'm afraid if we upgrade to 2019 we will have the same problem with this user.