Code 10 -device will not start

I'm new here, my first efforts were met with a driver problem COM3 "Code 10 - device will not start" and ""best driver but it may not work". Thing is my board (UNO) works fine on one PC but not the other. Both are Win7 64 bit - but the one that works is 1 yr old and the other new. After requesting help, and several downloads restarts... I finally gave up and went to the store (Radio Shack) and asked if I could plug in to another board. Did so and this brought up COM4 working fine. Took it home and swapped the boards. Then I uninstalled the COM3, reconnected the new board and it went back to COM3 Code 10. So I connected the old board and it came on right away with COM4 working properly. So I reversed sequence and connected back to the new board and seems ok. So I am functional or at least can be with the right sequence between boards. Still is a problem if I want to run either board.

I believe some boards have a bug in the firmware on the USB chip on them. This can be corrected. Check the firmware revision for both boards, see screenshot:

If one has an older version this page may help:

I'm not saying this will fix it, but it might. After all, you are saying you have two boards, and one works and one doesn't, right?

No both work but I have to pick one to be inoperable. Either one can be selected but I would have to uninstall and reinstall on the two COM ports switched to swap which will work.
Consider this -none installed. I take one board -either of the two I have, and install. I get code 10. Leave it and connect the other it'll install right off full operation. If I uninstall the first the second with code 10. So if I want to use board "b" I must install board "a" first (gets the code 10) then install "b" works.
I did try to disable and install - got two disfunctional "code 10". So if one board goes elsewhere and I want to use the remaining one I will have to make the leaving one go code 10, or I suppose borrow a board to get it code 10 so mine would be functional.

Doesn't make sense but seems to be consistant.

Thing is my board (UNO) works fine on one PC but not the other. Both are Win7 64 bit

Same hardware vendor?

Is a USB hub involved?

same vendor no hub

What device driver version numbers show up for each board? (see my screenshot above)

I do not see "Firmware"
there's a "Driver Key" and those numbers differ - one ends in 0001 the other 0000. I picked Driver Key because driver seems to be a factor otherwise ???

I can't see Driver Key. But it looks like you might be advised to upgrade the firmware on the chip that shows up as 0000.