<a href="http://community.eu.playstation.com/t5/Technical-Help/Please-help-with-error-80048A21/td-p/10690587;jsessionid=09CA8B56DF216FB08E7816B392D584D7">This</a> thread at the Playstation website suggests that rebooting is an easy fix. Have you changed your password for Media Go recently? Some seem to suggest that this error is caused by an incorrectly stored password, in which case restarting Media Go and entering the correct password should fix it.