cannot find attribute 1 of relation (of some user table) in 7.1.3

Hi, I have the follow problem when vacuum'ing on 7.1.3:

db1=# vacuum;
ERROR: cannot find attribute 1 of relation docmatchsel

I cannot drop the table either and the system does not seem do know
the columns:

db1=# \d docmatchsel
Table "docmatchsel
Attribute | Type | Modifier
-----------+------+----------

db1=#

Then I tried to reindex the table in standalone mode which gives:

backend> reindex table docmatchsel force
ERROR: catalog is missing 4 attributes for relid 117042636

I also reindexed the system tables to no avail.

docmatchsel was created as a temporary table in the application. No
indexes were defined for this table.

I cannot get either run vacuum nor pg_dump with success.

Is there any insight to this? I looked up the email archives but could
find a way to get rid of this problem.

Dirk