Configuring Error Messages in SSRS

Is there a way in which I can re-direct an unauthorised user who tries to view a report in SQL Server Reporting Services to show a custom error message rather than show the unfriendly SSRS error message that appears?

If I created a report and set a 'Jump To Report' variable, then this would always jump to the error message if the user clicked on a link to jump to another page, which wouldn't be what we want, would it?

Any help/ideas appreciated
Matt