How did you install PuTTY? What exact package did you use?
Does this registry key exist?
What does the key contain?
What sessions do you see on the PuTTY login dialog, when you start PuTTY 0.71? Do you see "WinSCP temporary session" there?
Does this registry key exist?
HKCU\Software\SimonTatham\PuTTY\Sessions\WinSCP%20temporary%20session
What does the key contain?
What sessions do you see on the PuTTY login dialog, when you start PuTTY 0.71? Do you see "WinSCP temporary session" there?