I have a fresh, brand new installation of Debian 9.
After installation was completed, I installed the NVIDIA proprietary driver and everything worked fine.
The problem started when I tried to install Steam, because out of the box, it doesn't work on Debian 64 bit; I have to install some packages like:
apt install libgl1-nvidia-glx:i386
Which only works with:
dpkg --add-architecture i386
The problem is after that package is installed, because now I have some broken dependencies and I cannot use
apt correctly, LibreOffice and Nvidia are uninstalled.
At the end, my whole system is broken and the only way for me to fix it is with a new fresh installation.
I have also tried
aptitude and the problem is the same.
aptitudeproduce, and then play Q&A session with folks who understand them. So I'd recommend to post a message to the
debian-usersmailing list instead.