Help! Error when calling a function

I am receiving the following error when I call a simple function:

Warning: pg_exec() [function.pg-exec <http://www.php.net/function.pg-exec>
]: Query failed: ERROR: fmgr_info: function 3036754: cache lookup failed .
in /var/www/html/cmwareben/db_pgsql.php on line 93
Database error: Invalid SQL: SELECT note_num,
fn_concat(rtrim(substring(note,0,40)), '...') AS note FROM feedback_notes
ORDER BY note_num
PostgreSQL Error: 1 (ERROR: fmgr_info: function 3036754: cache lookup failed
)
Session halted.

Here is the fn_concat function that I am calling

CREATE FUNCTION "fn_concat"(text, text) RETURNS text AS 'begin
return $1 || $2;
end;' LANGUAGE 'plpgsql'

I have the same function in another DB on the same server and it is working
fine. The only change I made to the DB was to drop the feedback_notes table
and recreate it with an additional column (New column = 'status'). The
select was working before I made this change and now it doesn't. No changes
were made to my PHP scripts at all! I hadn't don't even call the new column
in my select.

What the heck happened?

Ben