Hello, and welcome to Sysnative!
I'm very sorry about our late reply. Not that you knew it at the time, but this is really a question aimed at Windows Update specialists, and since this wasn't in the Windows Update forum because you didn't know that that was relevant, it went under our radar. I'm sorry for that.
Anyway, as I've hinted at above, the COMPONENTS hive - first introduced in Windows Vista, but tweaked several times over various Windows versions and service packs since then, holds a large amount of data associated with Windows Update configuration & status.
It's not considered a boot critical hive - and your computer will usually appear to function correctly even if it's corrupt/damaged/wrong/whatever (although if you do some very specific messing around with the reboot flags & update installs pended over reboot you'll probably be able to stop your computer booting into anything other than Safe Mode, but usually we consider it a non-boot critical hive. The trouble is that altering it in any way can severely mess up your Windows Update configuration, and you'll likely not be able to install or uninstall updates or Windows Features, and perhaps even some Windows Installer based programs if you're really unlucky.
For this reason, I strongly advise against using backups where at all possible. If you haven't install any updates (or had any installed silently alongside other programs etc.) since the backup, you'll probably be fine. If, however, you try to restore an old hive from before the last patch Tuesday, or worse, from another machine (which you should never, ever do - different program configurations which bundled different versions of different updates, different hardware --> different driver updates, whether or not the machines installed IE10 over the top of IE8, or over the top of IE8 and IE9 - all subtleties which make a massive difference), who really knows what will happen. Usually you'll just get an error if you try to use Windows Update, but it's worse if it tries to install updates it shouldn't do on your machine & puts your Windows folder out of kilter, or fails to offer you necessary security updates because it thinks they're already installed.
You could argue I'm scaremongering here - and in a way I am, because I'm highlighting the worst case scenarios. The trouble is that I've worked Windows Update issues for very many years, and I've seen many times where people try to be clever and copy a COMPONENTS hive from another computer, and it fixes they're Windows Update problem! Great! But somewhere deep down things are out of sync, and then everything goes belly up next patch Tuesday. Or the one after that.
Basically, the COMPONENTS hive needs care because incorrectly altering it often, in the best case scenarios, leads to no immediately apparent problems. But you've just set a time bomb for some particular update Microsoft will eventually release to touch an out of sync component & mess everything up.
Does this sort of help? Any more questions? I'd be very happy to answer them to the best of my ability :)
Richard
