I ran a complete scan on both my computers and didn’t find any problems.
Also ran Norton Power Eraser.
Also had Norton chat support take over my computer and try to find a problem within my computer, but no luck.
In case it’s useful, here is a description of the issue from Norton:
I just visited one of my infected sites (but recently cleaned with the Anti-Malware program). As soon as I went to it, the Norton “mass injection” warning came up, saying it just blocked “Web Attack: Mass Injection Website 14″.