C# – Open website in the user’s default browser without letting them launch anything else

I would like to open a website in a user's default web browser, however since the url is user-defined I would also like to prevent them from doing anything other than opening a website.

I have seen people use Process.Start(url); to open a site in the default browser, but since the url is user-defined I want to be sure they don't enter something like a script location and execute it.

I also don't want to use Process.Start("iexplore", url); since I would rather open the link in the user's default browser.

Is there a way I can open a website in the user's default browser, without letting them launch any other process or command?

EDIT

For example, I don't want users to be able to enter C:\Windows\Notepad.exe into the Customer's Website field and open Notepad when they click the Website link

EDIT #2

I am not looking for a way to filter user's access online or have this substitute for property security. I am simply looking for a way to prevent users from launching any other application by entering in a bad url. If they enter "google" for a Customer's website, it should not throw an Open With file dialog, but instead launch the user's default web browser with the word "google" in the URL