The short answer is: I don't think you can do this.
The not so short answer is: You could check from which computer/IP address a request originates by checking Request.UserHostAddress, temporarily store this IP address "somewhere" and prevent displaying the page to the same IP address again. But there are some problems with such an approach:
- you will have to clear the list of "active" client IP addresses sometime
- you will not be able to distinguish different users/computers if they are behind a firewall/proxy/etc (they will all show the same IP address to your web app)
