Url for sort by now working when logged in

Hi,
I’m using this query to get the most rated post:
http://www.yourwebsite.com/?r_sortby=most_rated&r_orderby=desc

it works great,but…
it works only if you are not logged in to my wordpress.
Once a user logged in to my wordpress system the query is not working anymore.

Any ideas ?
Thanks,
Elad

http://wordpress.org/extend/plugins/wp-postratings/