Cannot vacuum! Stops on first table, pg_type

Hi!

This is really strange. Starting from the beginning, I was running
postmaster with logs redirected to a file (on a different
filesystem). This has been going OK for quite some time. Suddenly, it
filled up quickly, and I had to rm it and restart the server this
friday. Today, it happened again; the log file area was filled up
completely by postgres' 700 Mbyte log file. I threw it away
immediately, so unfortunately I don't have these logs handy (I think I
can find some on tape, though...umm...). Have set up this machine to use
rotatelogs(8) (from apache) now, like on most of my newer machines :)

Also, when this happened, two postgres processes went amok filling up
the data directory with pg_temp.$$* files. About 25000 files (more or
less empty, if memory serves me) before I realized this had happened
(maybe a minute or two...?) Ran out of file descriptors, it was really
hot for a while :)

I shut down postmaster and removed them, since nothing worked anymore
while they were there (I guess postgres couldn't create more tempfiles
in that dir :)

Now, $PGDATA/pg_log is about 480 Meg. Hardly normal, heh?

# ls -l /usr/local/pgsql/data/pg_log
-rw-------  1 pgsql  pgsql  471556096 Aug 29 02:09 /usr/local/pgsql/data/pg_log

But:

# df -k
Filesystem              1K-blocks     Used    Avail Capacity  Mounted on
...
/dev/da0s1h               1986495   120813  1706763     7%    /usr/local/pgsql/data

Used 120 MB, but the file is 480 MB? One of those files with "holes"
in them, I presume?

Anyway, please note that the PGDATA file system was never filled up,
only the log FS.

Long story, sorry, but I thought it be best if no details were left
out...

The problem now: After the last incident, I cannot vacuum one database
(the big one)... other DBs are all right, but that doesn't help
me... :-/

vacuum stops on the very first table to vacuum, pg_type:

StartTransactionCommand
query: vacuum;
ProcessUtility: vacuum pg_type;
DEBUG:  --Relation pg_type--
DEBUG:  Pages 6: Changed 0, Reapped 2, Empty 0, New 0; Tup 354: Vac 22, Keep/VTL 0/0, Crash 0, UnUsed 0, MinLen 105,
MaxLen109; Re-using: Free/Avail. Space 8160/176; EndEmpty/Avail. Pages 0/1. Elapsed 0/0 sec. 

Here it can sit for hours (believe me, I've tried!) eating CPU time
(top(1) reports 95-100%)

Killing the vacuuming psql off (kill -TERM) gives:

proc_exit(0) [#0]
shmem_exit(0) [#0]
exit(0)

I seems, the database and it application is working OK, but my guess
is some indices are probably broken, so things may fail that I cannot
see immediately, and I can't vacuum to fix this...

Can I do anything besides pg_dump; dropdb; createdb; psql < dump.sql?
This server is live, and I'd rather not take it down for more than
seconds, if possible. Also, this should really be recoverable, right?
What about the large pg_log file?

I use this combo:

FreeBSD-3.5 RELEASE
Postgres 6.5.2

--
Palle