ports.tar corrupt?

[Dave Horsfall]

I don't know what it is with MacPorts and me, but here's the latest 
problem; when doing my weekly "port upgrade outdated" I get:

    Warning: Port cairo not found: 
    Warning: It looks like your PortIndex file for rsync://rsync.macports.org/macports/release/tarballs/ports.tar may be corrupt.

Etc.

How do I fix that?

Thanks.

-- Dave