Blame Microsoft for delivering Windows Upgrades disguised as "security updates". AD honestly thinks you've upgraded your PC.
 
This is one of the reasons I have disabled Windows Update completely on my Windows DAW. I'm not particularly proud of that, but Microsoft's behavior with respect to Win 10 just makes me fume. I can't trust them not to release an update that removes features from the OS.
 
Seriously considering moving my DAW to a Mac when SONAR supports it.
 
 

I am pretty sure Microsoft didn't consult XLN prior to adjusting IDs. Those IDs are intended to be static based on hardware, so Win10 altering them was not on most people's radars. AFAIK this was an anniversary update (1607) but never researched the why on it.

Adobe has used the same strategy for a lot longer than XLN to track 2 active licenses.

I just hit the same problem today, thanks to Windows 10 update 1607.  I went to my XLN online authoriser and see that it's happened before as my existing '2 only' authorisations were for W10, when I went from W7, and a previous W10 update that knackered AD2.  I de-authorised the first one and requested authorisation for my new computer: 'Build 1607 Sep 16'!
 
I wonder what else has been broken....
 

bitflipper
I'm surprised at how forgiving all you guys are toward XLN. 

If people can be forgiving of me, XLN should be a breeze to be forgiving of.

I was also running into issues with Pianoteq audio dropouts (it's just a sim, no samples or anything) and although SONAR was running everything through my interface as usual, it turns out that Pianoteq had disabled my ASIO drivers and was instead running the standard Windows drivers. I'm assuming this was also due to the Windows update. 
 
I agree that Windows shouldn't be updating things that are going to mess up existing hardware/software configurations, so that is frustrating. But on the other hand, none of my hardware changed and my computer ID remained the same, so you'd think AD2 wouldn't be recognizing it as a different computer. 
 
Frustrating all around. I was really digging Windows 10 up to this point, now I'm a bit more concerned about what the future holds if they continue to do updates like this. For people just using a PC to surf the web, watch YouTube and check email, I'm sure there are no issues. But folks like us who've invested a bunch of money into hardware, plugins, virtual instruments, etc. and have to keep everything talking together...man. We need OS stability.

henkejs
Same thing happened to me after the Windows update yesterday. AD2 is now working OK, but I'm still tracking down the other changes Windows made without asking me; e.g., changing my default audio device.

Don't you just love how "helpful" Microsoft is?

bitflipper
 
 
I'm surprised at how forgiving all you guys are toward XLN. Yes, they do make the process painless (if your DAW is on the net) but I still fault XLN for basing their ID on components that Windows Update can alter. That's not a good design!

This.  No reason an update to the OS should stop the software in its tracks, not related to a total hardware overhaul.

Moving to a Mac? That's even worse. There are quite a few VSts that stop working when a new OS comes out. At least you have a work around instead of 1) upgrading and waiting until the manufacturers update  or 2) don't upgrade yet. Then again, at least you have the choice to not upgrade.

the Win Anniv update was not good to me when I did it a few of months back.  I'm a Windows Insider (current build 1607 1493.187) so I get some early updates.  I've had to install many programs and VSTs, some had to be reregistered.  My XLN account had that glitch, but it also corrupted some installer files that took them a week to fix the issue.  I've had some Win updates since then that required some form of authentication or registration to repeat, but they work fine afterwards... just a pain to manage all of the licenses for waves, XLN, cake, IKM, and others that are not a permanent user authentication.  I won't even buy anything with ILok... just one more thing to deal with.  

There's a reason they call it being on the "bleeding edge", Maarkr.