vacuum: out of memory error

Hi all,

I have few of these messages in server log:

ERROR:  out of memory
DETAIL:  Failed on request of size 262143996.
STATEMENT:  VACUUM ANALYZE tablename

There are few of them, always the same request size(?) but different two
databases (out of 100+) and few different tables (pg_listener,
pg_statistic and few slony tables). Vacumm analyze is issued by
pg_autovacuum.

We're also seeing strange behavior of listen/notify in possibly
corrupted database: there are notify events being received by listen
process which the process didn't subscribed to. Can this be connected?

I've done little research in mailing list archives and I found possible
cause: table corruption caused by flaky hardware. Does it sound about
right? Are there any other possible causes?

What can be corrupted? How can I check it? How can I correct it? What
are possible consequences of this corruption? How can I investigate it
further?

It's Postgresql 8.0.6 on Linux.

Any help would be greatly appreciated.

Thanks,

Kuba