incorrect checksum in control file - Mailing list pgsql-general

Today I tried to move a database and got this error, which I gather is
very rare (also undocumented):

postgres[2767]: [1-1] FATAL:  incorrect checksum in control file

I moved the database from a 32-bit arch to a 64-bit arch.  All I did was
shutdown a 7.4.1 database, shutdown the machine, swap the storage onto
the 64-bit machine running 7.4.5, and try to restart.  No dice.

Any suggestions?  I copied the entire $PGDATA tree, reinitialized, and
restored from a dump.

-jwb