BUG #4948: getting error while vacuuming the database

The following bug has been logged online:

Bug reference:      4948
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

the same appears using vacuumdb command

vacuumdb: vacuuming of database "proxylog" failed: 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