[CentOS] Sector 0 I/O error harmful?

Fri Mar 28 10:56:10 UTC 2008
Sean Carolan <scarolan at gmail.com>

I have a bunch of these scattered through /var/log/messages on a
couple of servers:

I/O error: dev 08:20, sector 0

The server functions just fine.  Anyone have an idea what might be
causing this error?