BUG #4943: getting error while vacuuming the database

The following bug has been logged online:

Bug reference: 4943
Logged by: fous
Email address: honza801@gmail.com
PostgreSQL version: 8.4.0
Operating system: Linux (CentOS release 5.3)
Description: getting error while vacuuming the database
Details:

hi

i'm getting this error while vacuuming the database.

proxylog=# VACUUM ;
ERROR: failed to re-find parent key in index "user_day" for deletion target
page 1441795

i've found one thread with the same error

http://archives.postgresql.org/pgsql-bugs/2007-08/msg00082.php

but was not fixed/resolved
does anoyne know, where the problem is?

thanks
fous