Hi,
I have a fresh install of Vista x64. NIS 2009 was doing the same thing before I decided to wipe the hard drive and do a fresh install (altough this was not the reason for reinstalling windows).
It seems that at least once a day NIS 2009 says live update has finished, please restart your computer.
Is that normal? If so, it is quite annoying. I got this software because it is light on the system and very user friendly. I had no idea it was a pest! 
It did not do it for about the first 30-45 days of using it. Then it started daily. Then in the fresh install of Windows, daily.
Thanks!