Error from index "pg_type_typname_index"????

Hi all...

I've a postgresql 7.0.2 used as a backend for a website. Randomly,
and not very frequently, an error pops up saying that the following
problem has happened:

ERROR: Cannot insert a duplicate key into unique index
pg_type_typname_index

The query causing it it's an innocent query that duplicates a table
in a temporary one, i.e.

"select * into forum_clone from forums"

That of course doesn't cause any problem 99% of the time. The
fact that it happens doesn't seem to be related to load, neither
vacuumize the db seems to change anything.

Now my question is: anybody has a hint on what mey be
happening in that darn 1%???

TIA,
Ciao!

/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/\/

Fabrizio Ermini Alternate E-mail:
C.so Umberto, 7 faermini(at)tin(dot)it
loc. Meleto Valdarno Mail on GSM: (keep it short!)
52020 Cavriglia (AR) faermini(at)sms(dot)tin(dot)it