My DAW computer was completely disconnected and relocated for a few days during Hurricane Irma.  The evening I reconnected it Windows 10 performed a cumulative update (Version 1703).  Today was the first time I fired up Sonar since reconnecting everything, and for the first time on this Sweetwater-built machine I had an audio dropout - "Audio engine stopped unexpectedly".  Also, the red HD light stays lit up for a solid 2 minutes or so after loading any project (the dropout occurred when I hit play while the light was still on).  After a few minutes the light goes away, and things appear to function normally.  I believe this is also the first time my Focusrite interface has been physically disconnected from the computer in the 2 years or so I've had the interface.  Could be completely unrelated, but I figured I'd check here and see if anyone else has had any quirks pop up in their system.  (BTW, I did not have the AD2 re-authorization issue mentioned in another post).  Thanks in advance for any feedback!

If you are referring to KB4038788 (the latest update) there is only one issue that I see on the www.tenforums.com  
A lot of us had unresponsive Edge browsers.  It would open but never load a page.  I had that problem on mine.  I uninstalled the KB4038788 (which included a restart) and the problem went away.  On a whim I gave it a second chance and reinstalled the update and it is working OK since, Including Sonar Plat.
 
I would suspect doing what I did may take care of your problem.  If not, you are going to have to use a full disc image backup to restore to the PC, to get you back where it was before the update, assuming the update actually caused the problems.
 

That update threw a monkey wrench in my laptop that took 2 full days to repair!!!!! Thankfully, everything is back to normal now but it was a real nail biter for that 48 hours!!!

Sidroe, what happened and how did you "repair" it?

...and now it's fine. Other than a single instance of Addictive Keys bumping the CPU usage from 14% to 26% (which I'm pretty sure wasn't the case before). But no HD light on for an exceedingly long time, and no audio dropouts. At least since I've been home. So who knows?

No issues here apart from the standard AD2 re-authorization.

I was trying to Google something on my pc yesterday and it didn't show what I was typing and sat there doing nothing. I'm pleased to read this thread as it may contain the explanation.

Grum.

After the update, I've had a problem with my desktop.  If I selected any of the desktop files, the file would disappear. The only solution I've had so far is to sign out and then resign in.  Restarting or shutting down and restarting does not help.