CORRUPT Database error?

system : debian 2.0
postgres version 6.3.2-13
(installed from debian package)

output from psql

alan=> \dt
ERROR: type id lookup of 18 failed
alan=> vacuum verbose analyze articles; (it does something similar
without selecting the table)
NOTICE: Rel articles: Pages 14: Changed 0, Reapped 8, Empty 0, New 0;
Tup 70: Vac 0, Crash 0, UnUsed 23, MinLen 175, MaxLen 6253; Re-using:
Free/Avail. Space 4452/4040; EndEmpty/Avail. Pages 0/5. Elapsed 0/0 sec.

NOTICE: Rel articles: Pages: 14 --> 14; Tuple(s) moved: 0. Elapsed 0/0
sec.
VACUUM
alan=> \d articles
ERROR: palloctup: cannot handle length -1231926931 tuples
alan=> \d articles
ERROR: SearchSysCache: Called while cache disabled
alan=>

basically, the database is fried, I have tried silly things like
creating a new db, and copying the files into it. searching the mailing
list...

I think it was caused by either postmaster comming down or perl (pg dbi)
stuff not cleanly exiting (supposition only - it could be anything!)

Some advice would be nice :),
eg. any tools to recover data from the db files (or a file spec?),

Thanks for any help

regards

alan