If you open two separate windows showing the same folder, then delete the sub-folder from one of them, does the file display in both windows update? Or does only the window where you deleted the folder update, or only the other one, or is it sometimes either or both at random?
opw62 mentioned earlier that both folder trees failed to update update, but in the video it looks like one updates OK and the problem is only in the tree where the deletion was performed.
Only the folder tree where the folders were deleted nat not updating and getting the error
Maybe it's both sometimes and only one at other times?
For me it's always between the folder tree where the deletions were done (by tapping delete key in folder tree)
When it happens, is it always the tree where the delete was performed (and maybe the other tree as well sometimes)?
Yes--See above
What do other people see?
Is there a pattern to when it happens in both? For example, does it only happen in the other tree if it also happens to have the deleted folder selected, and never when another folder is selected?
Normally I can't tell because the only way to exit is to close the error window. In the past, I've alway just closed and reopened the lister so I can't tell you. If this cause I've left all three Windows open, and will try any testing use wish.
Does this happen in all folders, or only in a particular place in the tree? (e.g. Does it only happen on a particular drive, or only below the My Documents branch, or similar?)
I've probably had it happen 100-200 times in the past 7 years--I working in Opus 24/7/12 hrs-- 
--some builds have definitely been worse than others. It has always has been "normal" paths like my screen shots.
Try other locations in the tree to see if the same happens there. Try different drives.
See above--never been drive directory related--except for my message earlier in the thread about what's sometime seems to spark it.
opw62's video shows it happening at the roof of what looks like a generic secondary drive. That's useful information. Trying on the C:\ drive may also be useful, to rule out anything particular about the drive (filesystem, speed, etc.).
My C drive is just an OS--don't delete much there-- 
For everyone else, please say where you see it happening, and try in different places to see if it matters. I gave the example of trying below /desktopdir but C:\ is another example if you can't use /desktopdir for some reason. (Just be careful not to delete anything important!)
The windows are open and I will trying to leave them there if Jon/Leo want to me try anything
What if you also open an Explorer window, then delete in Opus; does Explorer notice the change?
See jpg-Explorer see the deletion.
opw62's earlier reply: "when I have Opus foldertree open and on top Windows Explorer and delete a folder in Explorer, then Opus is updated immediately"
But that wasn't what I asked. The deletion should be done in Opus. The question is whether Explorer sees the folder being deleted when you delete it from Opus.
New question: Does it only happen with lots of nested folders being delete?
As you can see in this case--No.
opw62's video shows it happening with lots of nested folders being deleted, so I made sure I did the same thing when trying to reproduce the issue. Is doing this important to reproduce the problem, or does it also happen with empty folders, and/or where there's just one or two things in a folder?
New question: What files are in the folders being deleted?
I was deleting folders in the tree with drivers extracts. I can replicate the folders easily--they were self-excrating driver files. I've attached one of the actual files.
opw62's video shows a few MB of files being deleted, from the progress dialog, but I can't see what they are. The file types are of particular interest. For example, if there are .exe files, archives or movie files, they can cause particular behaviours which may be relevant. I'd like to make my test as similar as possible by adding similar files to the folders I am deleting, in case it is important.
I have a hunch this is important, from an idea about what may be going wrong, but it is only a guess so far. I might be wrong but please do not ignore this question in particular..
See above.
New question: What does the file display look like? In particular, is it in flat-view mode, or doing anything which would cause sub-folders to be inspected in the background? (e.g. Calculating folder sizes automatically.)
No. Normal (at least for me)--dual listers with dual trees.
The video shows the folder trees but crops out everything else. As much detail as possible is always useful.
New question: Are you deleting with or without the recycle bin?
With--I've got delete to recycle bin whenever possible checked.
opw62's video shows the recycle bin being used. Is it the same for everyone else?
The questions on their own, so they are easy to go through one-by-one:
If you open two separate windows showing the same folder, then delete the sub-folder from one of them, does the file display in both windows update? Or does only the window where you deleted the folder update, or only the other one, or is it sometimes either or both at random?
The strange thing is the example is that the upper lister in both instances shows the two folders I deleted (asm104 and asmsata), but the bottom lister do not
Window with error
Explorer -- deleted directories not displayed
Other Opus lister open prior to error
example.zip (1.23 MB)
so I used a testdrive with a bunch of folders.
