how to Prevent Postback Events from Firing on Page Refresh

 when I am developing a web application I am facing the below mentined problem::

 Button_click event is fired when user hit refresh (F5) in browser. 

This behavior is easily reproducible:
Place ASP button on Web Form
1. Add some code to Button_Click event
2. View page in browser
3. Check that your code being executed when you hit button
4. Refresh page and observe that your code being executed once again


Can any one give me solution how can I prevent it. I am writing code using c# 2.0

Tathagata 

 
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