You may want to contact Nero. When serial numbers leak out and Ahead gets wind of them, they build those serial #'s into their code, as being invalid. Did you register your serial # with them? That is the best way to stay safe, in that, if you have problems like this, they have a record of you and your serial #.
I had to email my info and serial to email@example.com and have them register it for me, when I bought Nero. I found that tidbit, on one of their pages, as at the time, their online registration wasn't complete/working yet.
Ya think since they are showing up on many major store shelves, including Walmart these days, you would think they would have some type of online registration system up and running already.