Ok guys it seems I have found the SOLUTION
It seems that onboard GPU drivers as with the latest Intel CPU's interfere bigtime with dedicated GPU card drivers!
What I did :
Download and install DDU program for a deep uninstall of your GPU drivers (look it up at Guru3D website)
Boot up your computer in safe mode
Run DDU and choose to uninstall your GPU ONBOARD driver (Intel 530 in my case)
(I left the installed GTX driver for what it was, even though as it seems now it isn't the latest release)
Reboot normally et voila!
I can run the latest version of Resolve again.
Program starts up normal and I tried a quick import and edit of a video file and it does work super fast with the dedicated RTX card compared to before where I was using the accelerated Intel 530 graphics.
Hope it continues to work fine but all seems good for now!
Hope this helps other people!