Hello,
There are certain folders which are hidden, mainly in C:...Documents & settings, such as "Local settings".
I do not see them in the folder-tree, but I see the in the files-window.
So I right-click while pointing on "Documents & setting" check properties and uncheck the "hidden" attribute, now I can see all those hidden folders in the folder-tree. This works until the next re-boot when all those folders are hidden again.
Checked in the "Preferences - folders - options" the 'hide protected....' is unchecked.
In the "windows explorer" preferences, once I set it to show hidden folders/files it stays such until a OS re-installation, how shell I fix it in this Dopus? 
Thanks
L.J.
I just realized I posted my reply without fully reading your post correctly. The topic I referred you to discusses how to HIDE folders in the Opus file display. What you've actually got happening is the reverse... you WANT to see the hidden folders. Sorry for any wasted time!
Anyhow, have you made sure in Explorers folder options that the 'Show hidden files and folders' option is CHECKED, along with the 'Hide protected operating system files' being UN-CHECKED...?
As for the examples you used - the base 'Documents and Settings' folder is not normally marked as hidden, though some folders underneath it are. More importantly, please confirm (regardless of settings) that you do or do NOT see the same Folder Tree behavior in Explorer as you do in Opus... Opus doesn't explicitly control what you see in the 'tree' - Explorer should actually still be handling that to some degree.
If you want to see hidden folders in the tree, see the 4th post in this thread:
Hello,
Thanks to all.
Made the proper 'adjustments' - it works! 
Thanks again.
L.J.
I'm wondering if I can get some help with this. It's not related directly to Directory Opus although I do have the progrm.
I can't get the "show hidden folders and folders" option in Win XP to stay on. When I apply it and reenter the dialog box it has turned itself off again. Does anyone else have any experience with this and what can I do about it.
Thanks for any help.
Jeff
copy this botton & paste 
[DOpus.ButtonInfo]
Name=Show/hidden files
Icon=22,9999999
Flags=2,0,0
Color=0,a0a0a0
Tooltip=Show/hide files & folders
Func1=Set HIDEFILTERATTR h
Func2=Set SHOWFILTERATTR
Func3=Select DESELECT ALLDIRS
Func4=Select DESELECT ALLFILES