You need to go to Symantec and read up on this behavior. It sounds a lot like some viruses that specifically targeted updates meant to detect the very virus that potentially infects your system.
What you could try is going online to Symantec (if not blocked by the virus) and running their online scanning tool.
You could boot the Symantec CD (if it is capable of such) and running a scan. Often, this will eliminate the virus.
You should ALWAYS watch for the key phrases (like the one you quote) and search for them on Symantec’s website. This may clue you in to typical attacks with that type of symptom, from which information you may learn how to combat the infection.
But this is a four year old question and needs to be closed.