Vacuum full?

Hi, everybody!

I am having a weird problem with one of the tables in the database...
It seems to be working fine, whatever I do with it, EXCEPT, when I try
to to VACUUM FULL, it sits there for a while, and then fails with a message:

ERROR:  No one parent tuple was found

Does anybody know what it means, and, more importantly, what could have caused it, and
how it can be fixed (dropping and recreating the table is not an option - it is fairly
large, and there is a whole bunch of other tables that are referencing this one)...

Any help would be greatly appreciated!

Thanks a lot!

Dima