Wow. Thank you, thank you, thank you.
I needed InDesign on the second computer because of a major project with
a short deadline. I was very frustrated not being able to get it to work
and spent about six hours over three days working on it.
The issue was that I was using a Dell 27'' Ultra Sharp monitor
(2560x1440) with the text set to 150%.
Resetting it to Normal, 100% fixed the issue. I had to lower the
resolution a little to be able to read the text, but it's fine.
I did try to search for an answer but never associated the issue with a
resolution issue. Never would have thought to do that.
I did mark the answer as correct.
Thank you very, very much. I appreciate you knowledge and your
willingness to help other people.
The issue is only present with a combination of Aero themes and large fonts. You could switch to a classic theme (I customized one for myself) and reset the resolution and font size.
Thanks again. I'll do that if I need the higher resolution.