The original design uses horizontal tabs for categories that are not related, and vertical tabs for pages that are sequentially related. In terms of usability and navigation I think it is not as intuitive as replacing the vertical tabs with a breadcrumb or progress tracker for the user to follow. What is the best way to present this type of navigation/menu?
To help clarify the question, the horizontal tabs contain the higher level hierarchy, and the vertical tabs contain the lower hierarchy. That is, when you select from the top tab, you get a range of vertical tabs that are displayed as a result.