I came from XP, one of the nice features of XP was that when I would browse through a list of folders, when I would click the back button, it would remember the spot I was in. Windows 7 remembers the folder that was highlighted, however, it does not remember the location of the scrollbar - Win 7 actually moves the bar so the folder is at the bottom of the window.
This is somewhat hard to explain, which makes it extremely hard to search for, so I'll provide an example.
Step 1 shows me selecting the ServiceProfiles
folder - notice how the location of the folder is halfway in the window, it's centered vertically inside Windows Explorer
Step 2 shows me inside that folder (normal behavior)
Step 3 shows after I click the Back button (or Alt+<) - the folder now appears at the bottom
of the Windows Explorer window, instead of halfway down the screen like it was in Step 1.
Basically, the scrollbar moves down (changes position), so that the folder you selected is at the bottom of the window, instead of remembering the position of the scrollbar.