No one has had the exact same issue, but FYI in case this comes up for you later:
I upgraded my hard drive a while back, from 500GB to 750GB. After that, Windows refused to update. All attempts by myself and my techie guys resulted in bumpkis, and I was told to just leave it as is. Which sucked because it left my laptop vulnerable.
Turns out, the problem is this: if you have an Intel processor and/or controller (not sure which is actually relevant to this), often when you upsize your hard drive, the older Intel Rapid Storage Technology driver fails to load essential dlls and you cannot update Windows. Some people reported that they hadn't noticed that their Windows and things like Security Essentials were not updating until something like Sigil with its need for Visual C++ came along and they could not install it.
So you have to update the Intel Rapid Storage Technology driver. But if you're on a laptop, Intel's own driver update will not work; it returns a failure due to your system being unsupported ("OEM"). But in my case the sad bastards at ASUS (which I thought was a pretty good company) don't put the driver on their website. But if you go to HP you can find it there and it works the same. I found this one,
http://h20565.www2.hp.com/hpsc/swd/p...&swEnvOid=4058, though it is 2011. There may be a newer one on the site if you dig deep enough. But in any case the 2011 worked. I was able to install the Visual C++ required for Sigil and install. Now I just have to update Windows, which will likely take all night.