strange vacuum problem fixed by itself after one day???

Hi!

Here's a strange thing:

Automatic vacuum failed this night, and so did the pg_dump.

Here's what happened when trying to vacuum today:

db=# vacuum verbose;
...
NOTICE: --Relation personer--
NOTICE: Pages 155: Changed 0, reaped 6, Empty 0, New 0; Tup
6004: Vac 1, Keep/VTL 0/0, Crash 0, UnUsed 10, MinLen 132,
MaxLen 332; Re-using: Free/Avail. Space 8980/516;
EndEmpty/Avail. Pages 1/3. CPU 0.01s/0.43u sec.
NOTICE: Index personer_personid_fname_idx: Pages 44; Tuples
6004: Deleted 0. CPU 0.00s/0.01u sec.
NOTICE: Index personer_personid_index: Pages 30; Tuples 6004:
Deleted 0. CPU 0.00s/0.00u sec.
NOTICE: Index personer_fnamn_idx: Pages 34; Tuples 6004:
Deleted 0. CPU 0.00s/0.00u sec.
NOTICE: Rel personer: Pages: 155 --> 154; Tuple(s) moved: 0.
CPU 0.00s/0.00u sec.
NOTICE: FlushRelationBuffers(personer, 154): block 153 is
referenced (private 0, global 2)
FATAL 1: VACUUM (vc_repair_frag): FlushRelationBuffers
returned -2
pqReadData() -- backend closed the channel unexpectedly.
This probably means the backend terminated abnormally
before or while processing the request.
The connection to the server was lost. Attempting reset:
Succeeded.

I tried several times, to no avail. So, I sat down and began
writing this mail, and for reference, I did a vacuum analyze
again, and whaow, it just worked:

NOTICE: --Relation personer--
NOTICE: Pages 155: Changed 1, reaped 6, Empty 0, New 0; Tup
6005: Vac 1, Keep/VTL 0/0, Crash 0, UnUsed 10, MinLen 132,
MaxLen 332; Re-using: Free/Avail. Space 8788/700;
EndEmpty/Avail. Pages 0/4. CPU 0.02s/0.42u sec.
NOTICE: Index personer_personid_fname_idx: Pages 44; Tuples
6005: Deleted 0. CPU 0.00s/0.01u sec.
NOTICE: Index personer_personid_index: Pages 30; Tuples 6005:
Deleted 0. CPU 0.00s/0.01u sec.
NOTICE: Index personer_fnamn_idx: Pages 34; Tuples 6005:
Deleted 0. CPU 0.00s/0.01u sec.
NOTICE: Rel personer: Pages: 155 --> 155; Tuple(s) moved: 0.
CPU 0.00s/0.00u sec.

How come? It was broken for more than half a day, and I did try
multiple verbose [analyze].

FreeBSD 4.1-STABLE Tue Sep 12 20:48:53 CEST 2000
PostgreSQL 7.0.2 on i386-unknown-freebsdelf4.0, compiled by cc

/Palle

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