Automatic update nagging

Windows XP's auto update finds something it wants for you.
It downloads and installs it.
It pops up a dialogue that asks you to restart now, or later. There is a bomb timer on the dialogue, so that no input is considered consent in 4:45.. 44... 43...
Later makes it go away, only to return after a couple minutes.

I've been using PCs since you could buy one. This is one of the most annoying things ever. I've put up with it for a year, but it's entirely broken and for all of the other updates they've done, Microsoft hasn't fixed it.

Downloading a huge backup of your site's databases? Burning a DVD? Doing some massive computational task? Screw you, we're rebooting whether you like it or not. You're only human, you can't stay awake forever (and if you want to hire someone on the other side of the planet and give them remote access to your machine to click the dialogue box for you while you sleep, best of luck to you).

I'm okay with a single nag. But what's the expected behavior for the "restart later" button? It's not "annoy me again in ten minutes". It's certainly not "annoy me again and restart if I don't respond because I'm making lunch."

What you want to happen is to send it away until you're done with whatever it is prevents you from rebooting right then.

Bad design happens, and I can see where update functionality like this probably doesn't go through a quality design phase. But really, a year of people complaining - a year of everyone at Microsoft being subjected to it themselves - and no one's thought to tweak this?

(btw, how to fix this)