Looks like you installed the Windows Genuine Advantage (WGA Notification KB905474) update, sneaked in under last months auto updates as a critical update when it is nothing of the sort. Unlike other critical security updates I don't think this one can be uninstalled.
The third mid-month "critical update" patch — which also got shoved onto all PCs with automatic update activated — isn't a patch at all, critical or otherwise. It's the new version of Windows Genuine Nagware, er, Windows Genuine Advantage.
With this little gem installed (905474), if Microsoft's computers can't verify your copy of Windows, your desktop gets plastered with all sorts of irritating, incessant nags. As far as I can tell there was little, if any, advance warning that this "critical update" (yeah, sure) was going to get rammed down U.S. users' throats in an out-of-cycle mid-month automatic update. I could find nothing but this press release, dated the same day Windows Genuine Nagware spewed down the Automatic Updates chute.
From where I stand, Microsoft has shown that it'll use Automatic Updates to shove any software change onto any system that it darn well pleases, any time it likes. This isn't a conspiracy theory. Microsoft isn't a monolith. There's no Big Brother or master plan behind it all, no Mini-Me lurking in the shadows. Instead, what we're seeing is a bunch of stupid decisions, propagated to a hundred million PCs, by people who have demonstrated, repeatedly, that they can't be trusted with the task.
So you might well be stuffed. Some time ago MS allowed for ratting on the org/shop that sold you the software as genuine and either getting a free upgrade to legit version or a reduced price, I'm not sure if this is the case now.
You might want to call MS and see what your options are, they are likely to be more interested in the seller, but unfortunately you never know with MS.