Maybe you have heard of this one Skuzzy.....
(keep in mind I am speaking XP or earlier here, not sure about Vista)
A friend of mine is network admin at a local hospital. When they get new rigs to set up, before they run ghost or their disc image or whatever, they ditch Norton AV (which sometimes comes pre-installed). They ALSO use a program that might even be free/shareware called NONAV
(NONortonAntiVirus), because the normal Norton uninstall doesn't remove everything. This NONAV rips it out by its guts though.
But whatever the problem is, I say BLAME COMCAST (even if you don't have it) it's all their fault.