Evitare visualizzazione errori framework .net

[the_driver]

Ciao a tutti , vorrei capire come evitare di visualizzare dal browser eventuali errori generati dal framework.
esempio, se un file non esiste non vorrei che si presentasse un errore del genere

Server Error in '/' Application. 
The resource cannot be found. Description: HTTP 404. 
The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable.  Please review the following URL and make sure that it is spelled correctly.  
Requested URL: /default.aspx  
Version Information: Microsoft .NET Framework Version:2.0.50727.3603; 
ASP.NET Version:2.0.50727.3082 

Utilizzo IIS 6.0. grazie mille