Sorry about the wording. I forgot to mention my first step was to use the Lenovo driver. That was when the problem first occurred. On the Intel driver site, they suggested applying drivers in a certain order, with the chipset first, so I did that, with no joy. Lastly, applied the Lenovo driver again, no change.
Disabling the Intel video, though, restores the ability to change the resolution, but only up to a max of 1024x768.