Looks like Norton has a forum where people discuss stuff like this.

By any chance do you have a System restore point from prior to your malware install?
If you do, you might try taking it to that restore point.

Otherwise, HP PCs typically have a hard drive partition containing the OS image. You should be able to create a windows install DVD/CD from the partition. Or get the system back to the original factory install. I know that's a royal pain, but it's the cleanest way to remove it.