On my system NOD32 is set to automatically update virus definitions but only offer program updates. I was running version 2.50.25 and even when I manually ran updates it said my system was up to date.
Today I went to the ESET website and was surprised to find version 2.51.26 posted.
I'm not sure what is going on with the automatic update system but it couldn't even find an update when I asked it to - if you run NOD32 you might want to check your version an update manually if necessary.
The download link is: http://www.nod32.com/index_dw.htm and you will need you susbcription user name and password.