That's pretty weird. Mavericks has this "open all the windows I had open before the reboot" behavior that I think is at the root of this. My guess is that if you delete the .dmg file for the installer, that Mavericks will stop doing this. Depending on the browser, it should either be on the desktop or in your downloads folder.
The other thing you should try to do is "eject" the disk image from Finder. Open a new Finder window and you should see the installer listed as a disk in the left-hand pane. There should be an eject icon to the right of it. Just hit Eject.
My guess is that it was mounted when you rebooted, and it just keeps getting re-mounted because Mavericks is trying to preserve your previous session. If you eject it, it shouldn't re-mount after you reboot again. Either way, deleting the associated .dmg file and emptying the trash will make sure that there's nothing *to* remount. That's probably unnecessary, but there's probably not a huge reason to keep the installer files around now that you're done with them anyway.
Thanks Jeromie. I'll check this out next time I apply an update. I believe this was happening even before Mavericks. I know that it's a discussed issue on the Apple boards and has been going on for quite a long time. I usually do eject the installation disk after I've run the Install, and that hasn't seemed to make a difference. I'll pay more attention next time, though, and we'll see what happens.
If you run across more information, please feel free to point me to it. Most of us use Mac as our primary machines, and I haven't heard anyone complain about this particular issue before. It's really odd.
This may be due to the 'saved state' feature in OS X. Here are some links with information on this and how to disable it:
- Mr. Gecko's Media - Blog: Fixing Restore Windows Bug in Lion