I am running Windows XP pro on my computer. When I went to shut down last night, it prompted me to install new updates before I shut down. The screen said:
"Click Turn Off to install updates and shut down computer"
and then it also said:
"Click here to shut down without installing the updates"
So, I clicked on the "turn off" button to install the updates before it shut down. 14 hours later, it is still "installing 1 of 3 updates" and it says "Do not shut off or unplug your computer. It will automatically turn off when the installation is complete"
I'm pretty sure the installation isn't that big and 14 hours to install anything is pretty insane. I don't want to shut it down though because I don't want to risk the chance of it losing any information.
I have seen this before as well. Go ahead and shutdown (hit the power button if you need to). After a restart, you will be prompted again, at that point, restart and the install will complete, should be fine.