Success! What was needed was to uninstall from my PC the View NX2 (probably corrupted) and reinstall a fresh copy. Now the transfer function works just as described above by Eyelight (thank you!). The camera button in transfer allows me to select the card slot. Thank you all for helpful suggestions!
As many have already pointed out, if you are using a wire-transfer of your images from your camera to your computer, you should STOP! Don't do it. It's totally unnecessary and a waste of time. Get a card reader and use it. Almost all laptop sold since 2010 have SD card readers build-in - use it. Why use card reader?
1. It's much FASTER - very much FASTER
2. It's much more reliable - much more reliable
3. It save your camera battery life - the transfer circuits in your camera is NOT optimized for low battery consumption - all other circuits are - so you are burning through your battery for no reason at all. Any one who has to shoot tether (like me who do product photography) can tell you how short their battery life is when shooting tether compared to non-tether - that's because of the non-battery-life optimized circuit of the transfer setup. Just don't.
4. You need to take out and re-insert the SD card REGULARLY for optimal performance. Look at the contact points of your SD cards - they have scratch marks on them - that's good - it's the "self-cleaning" contact designed on the receptor end of the card. Every time you insert and remove the card, you are cleaning the contacts. Do it often. If you don't, and use wire-transfer only, corrosion will eventually build up on those contact when left unmolested for a few month or more. Our shops repair facility makes easy $10 when people bring in their cameras with "card err" - and when we find out that they have not removed their cards since they don't know when, all we do it take out the card, reinsert - and voila - it works. "That's $10 Sir!"
I suspect the camera manufacturers really never intend for user to use their wire-transfer 'cos all the ones that I've seen have such awful user interface and so annoyingly slow! It may be just an un-intended feature made available when they implement tether-shooting.