Not sure there's much you can do. instead of 'reinstalling' - try 'nuking' the AppData, Roaming Profiles, system18.1... directory for your OS user. Then try again.
if that doesn't work, then try extracting the 18.1 zip to a FRESH directory.
Jeff - About what I expected, but wow that was fast!! I will follow your suggestion. Assume it worked if I don't follow up. Thanks for your willingness to help out the SQL Dev/Oracle community. Much appreciated.