Good afternoon and thank you for posting on the Final Fantasy XIV Technical Support Forums.

If they have never played the game on this PC successfully, try updating Windows. Make sure to install any 'Optional' or 'Recommended' updates as these may not have been installed automatically.

Make sure that any anti-virus program they have has the appropriate exceptions for Final Fantasy XIV.

If it was not done while reinstalling the game, remove the locally-saved data folder (located My Documents > My Games > Final Fantasy XIV).

Remove any overclocks (including any factory overclocks) on the GPU.

I do want to note that if they no longer have a subscription on the account, they won't be able to log into the game to troubleshoot the issue.

I've also edited your post to remove personal information.

We hope we can be of assistance in helping you enjoy the exciting world of Final Fantasy XIV!