Inaccessible table??

Hi folks...need some help with data recovery. I've been using
postgres somewhat successfully (success - reliability problems)
for about a year. Today I have run into a major problem:
I have a 1.6 million record table, and I cannot get access to
all of the data in the table.

Specifically:
   1. The table is visible to clients - i.e. you can attempt
      a select, pg_dump, etc.
   2. If a pg_dump is attempted on the table, only the first
      761 rows are dumped. Thereafter, the server task spins
      forever chewing up CPU cycles and never dumps an
      additional record. In once case (prior to me killing the
      task) I witnessed it consuming 4 hours of CPU time.
   3. vacuum does the same...If I vacuum the db, it vacuums
      almost everything but this table (i.e. it gets stuck
      on what I think is this table). If a vacuum the table
      directly, the server task spins endlessly.
   4. Select statements hang forever (same effect)

All other tables behave "normally".

I have some rather important data collected in this table
over the past 8 days (since the last backup), and would like
to try to recover it if at all possible. Any ideas?

Thomas