On a Windows Vista or Windows Server 2008-based computer, you have a folder that contains many layers of subfolders. Each subfolder contains only one subfolder. When you try to expand the parent folder in the Windows Explorer navigation pane, Windows Explorer expands the folder to the last level of the subfolders as long as each subfolder contains only one subfolder. This problem may cause Windows Explorer to crash if there are many layers of subfolders.
If you have a subfolder that contains two or more subfolders, Windows Explorer stops expanding the folders when it reaches the folder that contains the two subfolders. For example, you have the following folder tree:
When you click the triangular icon to expand the C:\temp folder, Windows Explorer expands all the way to the C:\temp\1\2\3\4 folder. Windows Explorer does not expand the subfolders inside the C:\temp\1\2\3\4 folder because that folder has two subfolders, 4a and 4b.
Note: This problem does not occur in Windows operating systems that are earlier than Windows Vista.