I am running Windows 10 and recently updated Directory Opus (DO) to Version 12.3 x64 Build 6183. In the past I had my system setup to launch DO when Windows started but also checked the item "Don't open any Listers". Now, every time Windows starts DO opens up a lister. I thought that my settings must have been corrupted so I opened up Preferences to check the "Don't open any Listers" option only to find that it is greyed out and so cannot be selected. I have uninstalled and reinstalled DO but that does not resolve the problem. Is this a bug or am I doing something incorrectly?
If you disable Explorer Replacement entirely (Preferences / Launching Opus / Explorer Replacement / Don't replace Explorer), then reboot, does a File Explorer window open instead of an Opus window?
If so, the problem is outside of Opus, and something that runs on boot is asking for folders to be opened.
It's often caused by shortcuts in the Windows Startup folder or similar. The folder which is being opened is usually a clue as to what is opening it (but not always).
I have the same issue. Explorer Replacement is disabled - and always has been - and there is no Windows Explorer window appearing on startup. Whenever I start Windows, Opus opens up a lister (does the same thing when I launch it manually). Don't open any listers is also ticked, so something is definitely wrong.
If you launch Opus manually, it will always open a new window. It's supposed to, as it assumes you ran it to use it, not just to start it in the background. (Starting it to run in the background only really makes sense if it's run automatically at Windows startup. You can do it explicitly if needed, but you have to go out of your way to tell it to.)
If it's opening new windows at Windows startup, try setting Preferences / Launching Opus / Startup to not launch Opus at startup, then apply the change. Wait 5 seconds. Then turn it back on again and apply again.
Check that Don't open any Listers is set in the Startup tab while there, in case you were looking at a different tab.