I came to the same result last week, also after upgrading and old XP computer to Windows 7. I wanted to put WL4 on it since it doesn’t require the eLicenser, which I want to keep in the studio.
Indeed, opening files by dragging them in the WL window works, but saving is impossible. But I seem to remember discussion here on this forum, where people got it working… If anyone remembers more than that, please chime in!