.com pollution

I found corruption in (my server) and killed/started BIND at
17:50 EST. My other servers and were not
affected. I saw trash like this via nslookup/dig: "com nameserver =
H.RÔT-SERVERS.NET". I did not dump the db so I can't compare TTL, etc with
you. A-I were also all corrupt.

Any idea how it started?