As some of you may know, I previously had a MAJOR issue (due to the intel graphics HD 4000 driver giving a Code 43 Error) when I tried the Automatic Win 8.1 update. So, I've been just using Win 8 (without any issues) all this time, but kept getting the nagging pop up from Windows asking me to update to 8.1 (which I always selected "Remind Me Later" as I didn't know how to disable that pop up).
 
Anyway, last evening when got on my DAW, Win 8.1 had (on it's own) initiated the install and was waiting for my instructions on either an Express or Custom install. I was very worried that this update would again crash my sys and tried to reboot to see if it will bypass the 8.1 update, but it came back to the same install screen......so, I chose Custom and went ahead. Everything went very smoothly/quickly in the update and I'm happy to say that it was a success. The good thing is I have backups (if needed).
 
However, I'm annoyed that Win decided to do this update without my consent .
 
Possibly a reason I didn't get another Code 43 error may be due to the fact that this time I'm using the defaulted PCI graphics card (HIS 7870) instead of the onboard HD 4000.......not sure, but it's all working :)
 
Just wanted to share this for anyone else who's on the fence to update to 8.1.   
 

Hello.  I'm glad the update went OK.
 
It is possible to tell Windows to only update on your command.  In the Control Panel, look for Windows Update.  In Windows Update, select Change Settings.  Mine is set on "Check for updates, but only install when I tell you to" (paraphrasing).
 
Have fun!

On my DAW which is W7, I completely shut off Windows update so it will not interfere in the background. My DAW is not on the internet so there's no point anyways.  I do all the updates when I first build , let them run for a few days, then pull the plug. Seems to take a bunch of cycles before it stops notifying you of new updates and in the meantime I'm setting up Sonar, Wavelab, organizing C drive, tweaking all my drivers, installing plug ins etc. 
My Windows 8 office computer is left to it's own devises and seems to never stop updating. The month I built it my internet bill was an extra $30 for the bandwidth used for those updates which were 3 GIGs! I pay $10 per Gig as I'm on the G4 network here in the bush. Windows 8 $ 85 - Updates $40 so far..Why can't they just write these programs correctly the first time..

BbAltered
Hello.  I'm glad the update went OK.
 
It is possible to tell Windows to only update on your command.  In the Control Panel, look for Windows Update.  In Windows Update, select Change Settings.  Mine is set on "Check for updates, but only install when I tell you to" (paraphrasing).
 
Have fun!

I also have it set the same as you (for the general Windows updates), but the one I'm talking about looks similar to this, but with only the options to "Remind me Later" or "Install 5 minutes, 10 min" etc...

Hey, Mesh.
 
I don't think I have seen that Installation message - it looks like one of the messages Win displays AFTER doing an update (telling you to reboot.).
 
So, I can't really advise you further.  I wish I knew more about Windows and how it works.
 
A simple work-around would be to disconnect your computer from your network during those times you are using Sonar.  This is a pain but you can be assured there will be no updating while using Sonar.  This solution won't work if you have other programs (Addictive Drums, for one) that require access to the internet (I stopped using Addictive Drums for exactly this reason:  grrr...)

BbAltered
Hey, Mesh.
 
I don't think I have seen that Installation message - it looks like one of the messages Win displays AFTER doing an update (telling you to reboot.).
 
So, I can't really advise you further.  I wish I knew more about Windows and how it works.
 
A simple work-around would be to disconnect your computer from your network during those times you are using Sonar.  This is a pain but you can be assured there will be no updating while using Sonar.  This solution won't work if you have other programs (Addictive Drums, for one) that require access to the internet (I stopped using Addictive Drums for exactly this reason:  grrr...)

BA, that's not the actual update message I got (couldn't find the pic online for the one I had), but it was similar with a title as "Upgrade to Win 8.1" without any other options but to "Remind Me Later, Install in 5 Min" etc....
Anyway, the outcome of all of this is that I'm now updated to 8.1 as a result and (so far) everything is working as it should.
My DAW is currently online and has always been since my first build in 2007......never had any probs with that. I actually have Addictive Drums 2 (my actual go to drums) and have never had any issues with the installer being online.
 
Of course, the problems of keeping an online DAW secure depends a lot on the sites you visit........I stay away from the "usual suspects"  and also have a good antivirus program.
 

Disable Automatic Updates... and you won't have any surprises.   

Jim Roseberry
Disable Automatic Updates... and you won't have any surprises.   

That might have been the problem Jim.......I think I had it on Automatic Update before the 8.1 update...
(as of yesterday......it's Disabled )