The physical versions of the discs are not the full retail boxed versions, but branded installers on DVD - for the longevity that you are suggesting. However, even with the retail versions of the discs, some will be manufactured with errors from the media itself or a violent shipment hat damages the disc somehow. In these cases, our support team is usually pretty good with providing replacement discs with proof of purchase. The vast, vast majority of these discs install with out issue.
After reviewing your tickets (there seemed to be a few of them), the troubleshooting steps the agents took were correct as not all customers properly maintain their machines or have the level of technical knowledge you may have. There is no way for an agent to know if you are a novice, and computer expert or a novice who knows just enough to think they are a computer expert. I've been doing support for Roxio on all levels for almost 10 years and not only I myself making common mistakes, I've seen extremely knowledgable people (even one or two with PHd's) make them as well. So, no one is immune. Otherwise, we'd be sending repeated new downloads, installers etc when in fact, the machine itself could be corrupt from a family member or have additional software that could be inhibiting the installation.
Anyway, there you have it. I'm glad our engineer, Sonic Boom, was online and able to help you resolve this issue and sorry for trouble. I reacted instantly to your situation once I was altered to it by one of our Guru's as did Sonic Boom and I hope that counts for something .