Netsky is one of those things that spoofs the 'from' address when emailing itself, so the fact that you got the email thing back doesn't necesarily mean that you have sent out a virus (especially if you don't know the alledged recipient, obviously).
The computer problems would be more of a worry, if your definitions are up to date, Norton should pick up that sort of thing. In short, I don't know what else you would do, sorry.
The computer problems would be more of a worry, if your definitions are up to date, Norton should pick up that sort of thing. In short, I don't know what else you would do, sorry.