Offline update!?!? or delayed update?

Currently my XP have installed SP2 and I am a dial-up home user, well I have leave my PC off for few days now since my PC hang while shutting down ( after “windows is shutting down” msg, whole screen is blue color background) then I try reboot it to take a look at the event log, fine. After doing so when I trying to shut down again it pops out “install update and shut down” option.
Well I never goes online by all chance but why that option is available??