Well, I looked into it, and yes, apparently Amazon.com does this sort of thing quite a lot. The banned one guy for three returns in one year. Granted, they were expensive items, but if they were really defective, they should take that into consideration, or state the policy somewhere and very clearly.
Yet another reason that draconian DRM is a very bad idea. No one should be forced to keep a device they can't use or pay for content they can't access.