what does this error mean?

Hello all,

I get this error message at seemingly random times when sending a 'begin'
query to the database. I am using Postgres 7.0 beta 5. I have a web-based
system based on postgres and each hit is a transaction.

RelationClearRelation: relation 166124 deleted while still in use

The relation number is different every time.
Does this mean the transaction is not beginning? My 'hack' fix is to issue a
second begin statement if the first one fails... but that is really weird.

Thanks,
-Andy