back button on vista SP1 file open dialog box

Since I installed vista SP1, the back button on file open dialog box is no
longer available for an earlier path. What I mean is:

1. "Open File" from any application that would pop up an open file dialog box

2. Navigate to some deep path, such as d:\program files\myapp\mydata

3. open a file from there so the dialog box goes away

4. Do step 1 again

5. at this point, the dialog box should still point to d:\program
files\myapp\mydata, however, the blue back button is disabled, so I cannot
easily navigate to upper level directories. Sure, there is the navigation
bar for the path, but it is not as convenient. It is a bit annoying if I
need to open several files within a vicinity.

Is there a way to have the blue back button enabled? such as modifying some
registry entries? thanks.