warnings about invalid "search_path"

I'm seeing some weired errors in the postgres logs after upgrading to postgres-9.1(.3) about the schema added by default to search patch

WARNING:  invalid value for parameter "search_path": "system_data"
DETAIL:  schema "system_data" does not exist

We do have a user named "system_data" and a schema with the same name...

Apart from these warning messages, there is not other problem about it and we are actually able to access any of the tables, sequences, indexes, etc from that schema with out explicitly prefixing the schema name to those relations.

I searched postgres mailing list archives for a solution to this problem but the only discussion that i found matching my problem is http://postgresql.1045698.n5.nabble.com/invalid-search-path-complaints-td5615554.html

Could anyone suggest what could be wrong with my setup and how to get past it?