Windows Authentication Problem?

Here i am using dotnet2.0 and c# in my application. Here i am using Forms authentication and windows authentication in my application.Here we need to implement logout functionality in my application.For that i developed Logout functionality and i have written code under this logout functionality  as FormsAuthentication.SignOut();
 
here it is working fine by clicking LogOut it is going to login form and when i click Back button in my browser it is automatically redirecting to application.
I need to block this redirection to application after clicking LogOut button.Please give me help regarding this.It is very urgent.
 
 
 
Thanks,
Vsbabu.
 
...