Shoutbox

Like people have said before, don't select automatic updates and installation if you don't want your PC do boot up automatically, easy as that. The PC will not boot up automatically then (if it was required for a certain update), but only shows you a reminder (which can also be configured in gpedit.msc, which is the proper way of configuring the stuff, including what foaly said).

Automatic means by default... 'automatic', so yeah, everything will be automatic, including booting up. If it didn't booted up by itself it wouldn't be 'automatic' anymore, and booting up is part of the installation of some updates because certain things need to be installed or updated after a fresh start, so....

Don't blame Windows (in this case), blame yourself for choosing the wrong setting....


PS: Also some people forget that if Windows encounters a serious bug, it will also reboot by default (can be set in My Computer > Properties > Advanced > Reboot and reset settings (or whatever it is called)). I don't have the link anymore, but there are also many similar stories where people left their PC idling and blame Windows Update for auto-rebooting eventhough they have selected Custom Install. In the end the fact was that their Windows installation was corrupted and encountered some errors from time to time and thus rebooted instead of simply showing an error message.