Youtube Downloader snag

A friend was running a patched version of YTD and accidentally upgraded to a newer version. Of course, it was downgraded to Basic from Pro because it detected that the older version was patched.
She uninstalled the upgrade but now, when she tries to reinstall a previous version, she is told that she cannot install an older version.
Obviously, something has been placed on her system to prevent a previous install. Do any of you excellent people who know the inner workings of computers better than we do know what we need to do to fix this?
Answer #1
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Answer #2
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Answer #3
Do a System Restore to a time from before upgrade, then try re-installing the previous version again. Or, try uninstalling YTD using Iobit Uninstaller, which will also clear the offending registry entry that’s giving her that message, then re-install the old version.
Answer #4
Thanks. We’ll give it a try.