Vacuum - Out of memory

I'm getting out of memory error when I try to vacuum a table (any table
in fact).

=# vacuum analyze code;
ERROR: out of memory
DETAIL: Failed on request of size 1073741820.

I'm running Postgres 8.1.1 on RedHat 2.6 kernel (HP server). I never had
this error before and I ran vacuum every night regularly.
When I ran the vacuum on a different server with the same identical
(cloned) database and settings, vacuum works fine with no error.

My maintenance work area never been changed. It's set to 1GB.
(maintenance_work_mem = 1048576).
Physical memory: 32 GB. Top utilities shows:

Mem: 32752736k total, 14948340k used, 17804396k free, 122732k buffers
Swap: 2144668k total, 165140k used, 1979528k free, 14265048k cached

I bounced the database and still getting the same error. I could try
decreasing the maintenance_work_mem but I have plenty of memory and I
need it to process my nightly jobs faster. Any idea why I'm getting
out-of-memory error? Thanks,
__

Husam

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