Bongo,
You can try this path instead with the
3 entry:
%SystemRoot%\System32\shell32.dll,3
If that doesn't help, then I have one more item for you to try. See if restoring the default
New - Folder item with the download in the tutorial below may be able to fix the icon for you.
New Context Menu - Remove & Restore Default Menu Items
Here's a copy of the default Folder.ico file.