New Computer - Quicken 2015 Starter reinstall claims that existing data is from Premier

I've been using Quicken 2015 Starter for years on my old PC. I just got a new PC, and I reinstalled the same software I'd been using (I kept the installer EXE all these years).

When I load up the QDF I've been using, Quicken automatically "converts from a previous version", then pops up an error message claiming that the data came from the Premier edition (it didn't!) and says I need to upgrade to open it.

Updating the the latest Mondo patch changes nothing. Attempting to restore a Backup file also gives the same result.

Sometimes Quicken will load up the Home screen for my data, then pop an error message a second later claiming it was unable to load the data.

Any advice on getting my Quicken data to load?