Okie,
Lemme explain.
Explorer:
Tools -> Folder Options -> File Types -> Search for Folder
Click Advanced
There is generally one open & explore.
I have made this open as the "Set default"
Now on even "Open each folder on same window", on double clicking a folder it opens in a new window.
How do i make it not the default one, as it was working fine before i made it default. As when you double click a folder in explorer view, the left side tree view expands.
But now a new window opens.
Hope this makes sense.