|sounds like SP3 being downloaded. Depending on your connection it could take a long time.|
What you can do is go into control panel/security center and turn off automatic update. That should stop whatever is loading up.
What I usually do is select notify me but DON'T download them. Then I load up the criticals using the custom setting. That way you can see what you are getting before downloading them.
Some HELP in posting on Computing.net plus free progs and instructions Cheers