fatal error on 8.1 server

I don't know what the exact version is but I am getting this:

FATAL:  database is not accepting commands to avoid wraparound data loss
in database "postgres"

How can I recover from this and why woud this happen to the postgres
database?  Has my server been hacked?  there should be no inserts or
anything going on.

Thanks,

--
Tony Caduto
AM Software Design
http://www.amsoftwaredesign.com
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