Internet Explorer 11 doesn't work in (one) Windows 7 Pro computer

I investigated this some months ago and have encountered it again.
This is a Windows 7 Pro 64-bit system.
When Internet Explorer 11 is installed, IE will open only briefly (a medium-sized blank window) and immediately closes.
Safe mode doesn't help.
Safe mode in IE doesn't help.
IE without addons doesn't help.
Independently downloading and installing IE doesn't help.
IE 8 works fine.
I've followed all the instructions I can find and still no luck.
I don't really want to reinstall Windows.....