Catastrophic failure msg-opening folder in Window Explorer

I have for years used a desktop folder which contains about 50 shortcuts to my most commonly-used data files or software packages. I prefer this folder to be opened in Windows Explorer because it is a nice simple two column list of shortcuts. I open it every time I use the PC (Windows & 32 bit). Since moving to Opus v10, when I right click on the folder in the Lister folder pane and select "Open in Explorer", I sometimes see a message box that says "Catastrophic failure". I click OK and the folder of shortcuts then opens as intended. None of the Opus logs under Help record this "catastrophic failure" event.

The message has appeared quite a few times, but it does not appear every time. There is no error code of any kind.

So this is a bug report rather than a request for support.

Does it still happen if you select Preferences / Launching Opus / Explorer Replacement / Don't replace Explorer and apply?

Does it only happen for that one folder?

Firstly, the one shortcuts folder is the only folder I manually open in Windows Explorer via a right click in the Opus folder pane.

If I try the test "don't replace Explorer" by opting for that choice in Preferences, then when I right click my shortcuts folder, the option to open the folder in Windows Explorer is not there (presumably because the folder will open in Windows Explorer anyway, because that's the setting I've just chosen in Preferences).

If I set the Launching Opus / Explorer Replacement / Replace Explorer for all but the following folders: and add my desktop folder of shortcuts to the exception list, and then go to the Opus folder pane and right click my shortcuts folder, I can still generate the Catastrophic failure message, but not every time. So the intermittent bug is there, if I chose to open the shortcuts folder with a right click rather than double (left) click the folder.

If I simply double click on the shortcuts folder on the desktop or double click the folder in Opus folder pane, the folder then opens in Windows Explorer.

What this perhaps reveals is that the settings in version 9 for "Replace Explorer for all but the following folders:" did not carry over after installing version 10, as I had the shortcuts folder in the exceptions list in v9 (I should reveal that in the myriad of Opus's preferences I could not find, after installing v10, the place where to flag that I wanted my shortcuts folder to open in Windows Explorer. This forum post has cleared that up.)

So now I'm back to being able to double-click the shortcuts folder to open it in Windows Explorer, and I will not see the Catastrophic failure message again unless I lapse into using the right click method in the Opus folder pane.