"The computer Whisperer"

Problem: Folders sometimes do not open in a new window when that mode is selected. (Vista)

Open Windows Explorer
by clicking on The Vista Pearl "Start" then hover mouse over "Computer"
Right click on Local Disk C: If Open is in bold selecting it would be the same as clicking Open w/o right clicking first.  To get automatic folder windows you must use Open and not Explore. 
Notice that with the folders visible in the Navigation (left) pane "Explore" is the default action for a double click.
Clicking on the down chevron above removes the folders from the navigation pane and makes the Open function the default action for the double click. A new window should come up now when clicking folders in the right pane.
Another way to Accomplish this is to eliminate the Navigation pane altogether.  Just make sure that in the Organize drop down Layout the Navigation Pane is not highlighted. If it is then click on it.
In this configuration folders will open in a new window when clicked as long as "Open each folder in it's own window" is selected in folder options.
Then with no folders showing in the Computer window or the Navigation pane not showing at all click on any folder and it will open in it's own window.