Hi, hope this will help someone.
My story in short. More than a year back. Bought UR242, plugged into USB port 1, installed driver, all works okay. Bought Yamaha MG12XU, plugged into USB port 2 (both are USB 2.0). System automatically took existing driver from hopefully the same place it’s taken for USB port 1. Naive me! I had dropouts on MG12XU, but not on UR242. Interesting, isn’t? If I exchange cables and insert UR242 into port 2 and MG12XU into port 1, then all was okay.
The time was ticking away and more than a year I had updating Yamaha driver, but dropouts always stay stable on USB port 2 for MG12XU. Also I realise that when I start my PC and Windows10 is almost loaded, Task Manager shows that he is working on system disk and it continues almost 5 minutes, sometimes less. I didn’t connect both issues.
Until yesterday when I computer goes mad and dropouts was killing my time wherever I plug my MG12XU. At last Cubase refused to work with MG12XU, but still no problems with UR242. As a last possible move I opened Devices and Printers - it shows both speakers, one for UR242, second for MG-XU, but it has a big red dot with X on it. Something went wrong, I supposed and after trying to reinstall/find newest driver, which didn’t help, I brutally removed MG-XU speaker from the list - rightclick and Remove Device. Then I switched off and on my MG12XU, it took newest driver and now I don’t have any problems - computer starts very fast, system don’t hang on checking system disk at startup as I described and I don’t have dropouts on MG12XU.
So, question is:
If we update Yamaha driver while using only one Yamaha/Steinberg hardware plugged in, does it ignore driver connectivity for other USB ports? (stupid question, but it seems so!) Everyday I use UR242 as main soundcard, but sometimes for record sessions I use MG12XU.
Maybe there is something like repository of old drivers on system? Yeah, it has, because we have function “roll-back” to previous version. So is it possible that USB port 2 uses old version of driver because I don’t use it when updating to newest?
Anyway this was good opportunity to learn something new - not like composing in C Maj 
Resume - if you have dropouts, remove device logically while physically it is plugged in. This somehow refreshes Windows understanding of what it has actual. IMHO 
And… Excuse me for my poor English. I’m Latvian and never learned English except tutorials and Youtube, of course
Have a nice weekend to all you!!!