I was able to reproduce this issue, but only using your CXR file.
I opened your scene and rendered it locally, saved a new CXR file in 6100 resolution and denoised it in CIE - everything was fine.
And I am using "only" a GTX 1660.
So it appears to be some issue on your end. Here is what I would suggest:
In V7, we do not install the specific Optix denoiser with Corona. Instead, we provide the one shipped with NVIDIA drivers, so:
1) Uninstall Corona completely
2) Go to C:\Program Files\Corona and remove this whole folder
3) Make sure you have the latest NVIDIA drivers installed in your system
4) Go to the folder where you have the V7 RC5 installer and make sure you
do not have any offline NVIDIA Denoiser installer in that folder (this:
https://coronarenderer.freshdesk.com/support/solutions/articles/12000048131)
5) Install V7 RC5 again using "custom" installation mode and make sure the NVIDIA Denoiser is selected in the installer
6) Try rendering the same scene again, save a CXR, try denoising it in CIE