Redirect if access is denied

I have the following web.config file in my MemberPages directory:

<configuration>
    <system.web>
        <authorization>
            <allow roles="member" />
            <deny users="*" />
        </authorization>
    </system.web>
</configuration>

If the User is a "member", he/she is allowed access to web pages in the MemberPages directory. Otherwise, he/she is denied access. The mechanism works. However, when the User is denied access, the following very unfriendly message appears:
    Server Error in '/MyWebSite' Application.
    --------------------------------------------------------------------------------
    The res ...