Linux Mint Mate 18.3 + GTX 460. Second monitor desktop not starting with separate x screen. / X.Org X Server 1.18.4

Setup:
OS: Linux Mint Mate 18.3 / 64 bit
Kernel: 4.10.0-42

Graphics card: Palit GTX 460 / 1Gb memory
Latest Proprietary driver (from repo): Version 384.90

Right (MAIN) monitor is DVI / Acer AL2423W (Screen 0)
Left (second) monitor is DVI / Samsung S27A650D (screen 1)

Motherboard: Asus P7P55D
Prosessor: Intel Core i7 CPU 860 (2.8 ghz)
Memory: 12 Gb
Bios: 2101

Fresh install of Linux Mint 18.3 Mate.

EDIT: nvidia-bug-report.log in post #6

When I set up proprietary driver (instead of nouveau), and in Nvidia X server settings I set the system for “separate X screens” The monitor nro 2 stays black, all I can see is normal mouse cursor, I can not do anything in there. Monitor 1 works normally.

When I start for example firefox for second monitor (with DISPLAY=:0.1 firefox), then both monitors start blinking in turns. Firefox does start on second monitor, but it seems something is badly conflicting, since output is so messed up.

Same thing was when nro 2 monitor was VGA-monitor, now DVI.

I need separate X screens, it is not an option to use something else, so do not ask me to do that.

Problem started from Linux Mint 17.3 and up to 18.3, and all variations I tested in between. In mint 17.2 everything works normally.

Any help here? Does someone have similar setup working?

Thanks.

No, just another user was also in search of his second screen. Something seems to have broken around xserver 1.18. Can you tell which was the last working combo of driver and xserver?

Currently working on Mint 17.2:

Driver version 384.90
Xserver 1.15.1

~ $ Xorg -version
X.Org X Server 1.15.1
Release Date: 2014-04-13

(Edited the correct version)

For example my Mint 18.3 has following (not working combo):

-Driver version 384.90

-X.Org X Server 1.18.4
Release Date: 2016-07-19

Mint 17.3 has same driver (384.90), but Xserver version is 1.17.1

So something went wrong between versions 1.15.1 and 1.17.1

Now using driver version 390.25, no change.

Here is fresh nvidia-bug-report.log --> http://pasted.co/faf88a96

Does anyone have the similar problem, and possibly a solution? I must upgrade my OS, since there is no support anymore for Opera browser and (chromium) flash (do not work together, so can not update Opera)