C6280: Can't select automatic two-sided printing

Hi:
I am using an HP laptop running Windows Vista 32-bit Home Premium.
I had previously fully uninstalled my HP Photosmart C6280 all-in-one printer.
Today, I reinstalled it using the CD-ROM that came with the printer.
When I went to print an MS Word document, I was not presented with the normal set of
Print options/settings to choose from.
I could not select Automatic doubled-sided printing: it wasn't in the drop-down menu.

When I selected Print from Word's File menu, a print dialog box opened: it's title was HP Photosmart 6200 Series Document Properties. From within this, I selected:
Properties > Printing Shortcuts Tab > General Everyday Printing.
in the lower right area of this panel, is a drop-down menu titled, "Print on both sides".
It offered the following options to select from:
Off, Manual, Left-edge booklet, Right-edge booklet.
The option, "Automatic" was missing from this list: previously, it was directly below Manual.
I do not remember if the Left/Right edge options were there before.
Directly below this drop-down menu is that for selecting Orientation: Portrait or Landscape.
So now, I am unable to do automatic 2-sided printing.
If I click on Duplex instead of General Everyday , I briefly see the word Automatic in the menu, but is replaced with Manual. Also, for this Duplex mode, the Orientation drop-down me u is missing/hidden. I do not know if it is supposed to be that way.

The Problem: Why do I no longer have the option to do Automatic 2-sided printing ?

Any ideas ?

Thanks

DaleBr