If a new SD card doesn't fix the problem, then return for a warrantee replacement. AFAIK, there haven't been any other reports like this, but given the number sold I would expect some failures in the field for faults that cannot be detected by the production line.
Not sure about the MPEG key.
Principal Software Engineer at Raspberry Pi (Trading) Ltd.
Contrary to popular belief, humorous signatures are allowed. Here's an example...
"My grief counseller just died, luckily, he was so good, I didn't care."