Stella decided to reinstall her computer, using the provided OS recovery disk.
She had a couple of abortive attempts which ended up in a blank screen and no reactions after setup was done and it had downloaded about 50 updates, but managed to persevere and eventually actually got the computer looking the way it did after we had bought it! (Including all the useless bundleware such as Medion Lotto and an eBay link on the desktop etc. etc.) Apparently, the secret was to include the Drivers+Applications disk at some point during the setup process, though she says she doesn't think she could duplicate her actions. At any rate, it works and that makes her happy.
The TV tuner works, too, though that's not so vital since she brought up the television set from the cellar which we had meant to sell but hadn't yet.