This error started happening only on computers with 1511 installed. The original RTM of Windows 10 doesn't do this, nor do Windows 7, 8 and 8.1. I tried some Google searches but all I see are relevant to 7 or 8, not Windows 10. It must have been something changed between RTM and 1511 that did it, too.
This only happens once, but let me explain.
When I refurbish computers for our employees, I wipe the hard drive completely (either diskpart "clean" via the recovery shell, or using DBAN to wipe the partition table if I can't get into WinRE.
I then boot it up using network boot. We have a Windows Deployment Services server set up so we can install Windows using PXE. I put the Windows 10 Enterprise Version 1511 .wim in there and it installs fine.
After install I make a local account, make sure the drivers get installed automatically (so far, it's been auto-magic for all our hardware, even NVIDIA and AMD graphics cards), install antivirus + MS Office and whatever special software that employee would need, and then I name the machine and put it on the domain.
To prevent extra crap from being created in C:/Users (and in the registry) I don't log in with a domain account. I let the employees do that themselves.
The first time any domain account* tries to log in, it errors after about 20 seconds with
If they put their password in again, it goes through and all the initial settings are applied from our Group Policy Objects.
Windows couldn't connect to the System Event Notification Service service.
Please consult your system administrator.
*I noticed that if I log in as an account which is a Domain Administrator (and via our GPOs, is also added to the Administrators group on the machine), I don't get that error. It only shows up for "normal" users which are not part of admins.
Nothing critical by any means as it will always work on the second try, but I'm really curious why it happens at all. What service is it even trying to connect to? The fact it happens on literally every computer (it even happens in VMWare images which I've done to test GPO settings) would imply it's not a problem with a particular machine, rather something in our domain. Or it's possible there's a GPO that was set years ago for Windows 7 that didn't cause any detrimental effects until now.
I'd be happy to provide diagnostic/debug stuff, just tell me what you need and I'll try it in one of my VMs!