I am running DisplayFusion 9.1 on Windows 7 x64. I have three monitors, let's denote them L, C and R. Windows is configured to use C as the main monitor, i.e. the "real" task bar is shown on C, and the DisplayFusion ones on L and R.

Occasionally (about 1 in 20 occasions), the monitors L and R are swapped. This can be observed by:
1. I pin different programs to the taskbar of L and R respectively. The pinned programs are swapped.
2. I configure L and R to use different wallpapers. The wallpapers are swapped.

In every instance, the issue can be resolved by rebooting the machine. Subsequent reboots will not reproduce the problem. However, after one to two weeks, it will occur when I boot up the machine. Again, a reboot will solve the problem.

This issue was also observed on DisplayFusion 9.0.

Yes, I am running Nvidia GeForce 980Ti. The driver edition is 388.31.

The graphics driver is not set to auto update. The issue occurs upon bootup, and there are no changes to any system configuration whatsoever - no driver update, no Windows Update, no graphics option change etc. From my point of view it is random in nature.

I will check for it next time it happens, but I am fairly certain the problem is within DisplayFusion itself. This is because the mouse cursor travels across my three monitors correctly, indicating that Windows register them in the correct order.

Alright, this just happened again and I am able to capture some info.

It appears that Windows mixes up the monitor numbers on occasion. If I right-click on desktop and go to Screen Resolution, the monitor number sequence is usually "3" "1" "2", i.e. "3" is the Left monitor and "2" is the Right monitor.

During the mixup, the sequence is "2" "1" "3", i.e. the Left monitor now gets the number "2". I presume DisplayFusion gets these numbers from Windows, and it uses the number as the identifier for what goes to which monitor. Since the monitor ID "2" is now assigned to the Left monitor instead of Right, what used to be on the right side appears on the left.

It is interesting that I have no issue moving the cursor across the three monitors. In both instances, if I check the monitor model associated to the numbers (I use a different model for each monitor), the association is correct. That means Windows remember the relative arrangement of my monitors correctly. It is just the number assignment got mixed up.

I guess the number assignment in Windows 7 was not important because the OS was not designed with multi-monitor support, unlike Windows 8. In Windows 7, there are only "main" and "non-main" monitors. As long as the main monitor is identified correctly, the rest will behave normally no matter what the number assignment sequence is.

It is a minor annoyance really, but if DisplayFusion can remember the settings by associating them with the monitor model rather than the number, the association will be correct each time, no matter how Windows assign the numbers.

May I suggest the following matching logic:
1. Remember both the monitor model / serial number and monitor ID.
2. During the matching process, the monitor model takes precedence. I.e. the config will go to the monitor that has the same model as the saved config, even if the number does not match.
3. For the remaining configs (if any), that all share the "generic" model, match with the monitor ID.

Kind of like the "SORT BY ColA, ColB" idea - I think you get the point.

Or there can be an option somewhere that allows people to select these two "monitor matching methods" to suit their needs.

Like I said, this is a minor problem really, and other functions in DisplayFusion are working well so I am not complaining (-; But if it can be improved, it would be fantastic!