V1R5 installation does not work - V1R4 corrupted - HELP

Dear,

I have a PC with Vista Home Premium. I downloaded this morning the new Drafsight V1R5, the installation starts automatically after download. Authorisation to install was granted. It stops in the middle of the installation. I retry from my temp library with a "Run as Administartor" It stops again. At this point in time, my old version V1R4 of Drafsight is NOT USABLE ANYMORE.

As I had similar issues with V1R3 and V1R4, I managed to delete manually the Dassault/Drafsight libraries. This time it does not work. I am stuck and cannot use Draftsight in any way.

The official support does not help as I did not pay the PRO support.

I can provided pictures of the screens

HELP !!!

Regards, Philippe