Hi Jacques
I'm not with Laminar Research, just a fellow simmer in the UK, but please could you advise which version of X-Plane 11 you are trying to install i.e. digital download from LR, DVD set from LR, Steam or any other?
Normally if you have a valid copy of X-Plane 11 from LR, the whole of it's root directory sits in your local C:Drive as a completely standalone entity, it in no way installs files in your Windows/MAC operating system or associated registries.
Please advise?
Regards