problem with pc-cillin 2005

i was using Pc-cillin internet security 2005, i've stopped using it about a month ago. the problem is the serial # is supposed to be expired on 2/15/2005 but a month ago it kept saying that the serial is invalid every time it tried to update. it doesnt matter how many serial # i tried, it still ended up with the same problem. i even tried to reinstall it but the problem is still not solved. any idea why?

the serial key you are using could no longer be vaild with the current build or version., or has already been black listed.

Ive been using AVG for a long time now and see no reason to waste time on ck AVG ffs...