Box D on my W2 form is blank. Turbo tax will not allow me to progress without entering something. What should I do?

Box D is not a required field. Evidently, something got entered here and when you cleared it, something remained behind to trouble you.

Did you auto-import the W-2? If so, delete it and enter it again by hand. In fact, no matter how you entered it, just delete it and start over - by hand.

On the first screen, be sure not to enter anything for Employer EIN, but just continue to the second screen and enter all the other fields (note: on the second screen, it's OK to enter the employer EIN - the problem with doing it on the first screen is that it causes TurboTax to try and auto-import the W-2 from your employer).

And on the bottom of the second screen just leave box D blank.