As with all consumer products, there are always faulty units being exchanged. I don't think the incidence is particularly high given how many have been sold.

It does appear some idiot has entered your Serial number into their system by mistake (probably a Typo) which has de-registered your TiVo.

Customer Support for TiVo here is woeful at best, and fairly non existent for the next couple of days at least.

Usually this type of issue can be fairly quickly fixed as it is obviously an issue at their server not your unit.

Peter.