Corrupt database

One of our PostgreSQL databases has been corrupted somehow.  Whenever we
try to open it or access it the 'postmaster' task suddenly goes to 99%
CPU usage, it rapidly eats up all memory, then crashes our server.

This behaviour occurs when the database is opened in using Perl's DBI,
or when using psql or pg_dump or vacuumdb.  There is about a megabyte of
text contained in this database which I'd rather like to extract
somehow.  Our other PostgreSQL databases are running perfectly.

Any suggestions on how to recover my data?  I've browsed the PG data
files, but they appear to be binary, which I can't read.

PostgreSQL 7.1.1 on Linux 2.2.19

Thank you.
--
| Neil D. Fraser, Programmer & Wizard, neil@digitalroutes.co.uk
| Digital Routes, Inverness, Scotland, www.digitalroutes.co.uk