Strange \copy failure

This is on postgresql 7.0.2, RH6.2.

I'm doing a \copy from psql of a 2035 line file, and the backend is
hanging (no CPU being used). Control-C doesn't cancel the command and
I have to Control-Z and 'kill %p' to get psql to terminate. The
interesting thing is that if I chop the input file in half, it
works. I can \copy the first half, and \copy the second half. Even
more interesting, if I take the first 2000 lines of the file it works,
and if I take the last 2000 lines of the file it works. This is a 2035
line file, so it makes me thing there isn't anything wrong with the
data in it.

For what it's worth, this file has been copied in daily for quite a
few months without problems.

Trying to \copy the whole file, the last few lines of postmaster
output are:

010614.14:00:38.425 [19753] query: COPY "allocation_header" FROM STDIN
010614.14:00:38.425 [19753] parser outputs:

{ QUERY :command 5 :utility ? :resultRelation 0 :into <> :isPortal false :isBinary false :isTemp false :unionall false :distinctClause <> :sortClause <> :rtable <> :targetlist <> :qual <> :groupClause <> :havingQual <> :hasAggs false :hasSubLinks false :unionClause <> :intersectClause <> :limitOffset <> :limitCount <> :rowMark <>}

010614.14:00:38.425 [19753] after rewriting:
{ QUERY
:command 5
:utility ?
:resultRelation 0
:into <>
:isPortal false
:isBinary false
:isTemp false
:unionall false
:distinctClause <>
:sortClause <>
:rtable <>
:targetlist <>
:qual <>
:groupClause <>
:havingQual <>
:hasAggs false
:hasSubLinks false
:unionClause <>
:intersectClause <>
:limitOffset <>
:limitCount <>
:rowMark <>
}

010614.14:00:38.426 [19753] ProcessUtility: COPY "allocation_header" FROM STDIN
010614.14:00:38.427 [19753] NOTICE: copy: line 1, CopyReadNewline: extra fields ignored
010614.14:00:38.428 [19753] NOTICE: copy: line 2, CopyReadNewline: extra fields ignored
010614.14:00:38.428 [19753] NOTICE: copy: line 3, CopyReadNewline: extra fields ignored
...
010614.14:00:38.598 [19753] NOTICE: copy: line 837, CopyReadNewline: extra fields ignored
010614.14:00:38.598 [19753] NOTICE: copy: line 838, CopyReadNewline: extra fields ignored
010614.14:00:38.599 [19753] NOTICE: copy: line 839, CopyReadNewline: extra fields ignored
010614.14:00:38.599 [19753] NOTICE: copy: line 840, CopyReadNewline: extra fields ignored

...and then it just sits there.

(the file has more columns in it than the database table, but this
shouldn't be a problem should it?)

If I do an SQL COPY rather than a \copy, it works fine.

I tried stopping and starting the postmaster, dropping and recreating
the database (with just empty tables, no data), and also creating a
new database (ie. different name), but nothing works. I'm a bit stuck
for ideas now!

In case it's useful here's the output from ipcs:

------ Shared Memory Segments --------
key shmid owner perms bytes nattch status
0x10feed01 0 root 644 25224 5
0x0052e2ca 8271873 postgres 700 144 1
0x0052e2c1 8271874 postgres 600 17227776 1
0x0052e2c7 8271875 postgres 600 66060 1
0x00280267 4 root 644 1048576 2

------ Semaphore Arrays --------
key semid owner perms nsems status
0x00feed00 0 root 644 2
0x0052e2ce 54273 postgres 600 16
0x0052e2cf 54274 postgres 600 16
0x00280269 3 root 666 14

------ Message Queues --------
key msqid owner perms used-bytes messages

When the postmaster is stopped, all the postgres owned lines go away,
so I don't think I've got any unattached ones lying around.

Does anybody have any ideas for what I can do to fix this?

Regards, Steve Woodcock