0
Hi Akshay,
The microsoft provides the technique to deassemble the code. Because there are some open source tool like Reflector will help the engineers to convert dll into code (reverse engineering).
You may hear the tool called "Dotfuscator community edition" in the .net framework. In the visual studio 2008 if you see the visual studio they have given that option.
what it does if the engineer try to do the reverse engineering, the code will be splited and they can't get the sequence of code.
Obfuscating can make code very difficult to understand or even reverse engineer. Programs written in .NET or Java are easy to decompile to full source code as though the cracker is looking at the original code you wrote in your IDE. These reverse engineering programs are freely available on the internet making it easy for anyone to see your entire source code. While still readable, obfuscating makes the code harder to read creating some security for your applications.
You can see the documentation and way to implement in the following urls:
http://msdn.microsoft.com/en-us/library/ms227240(v=vs.80).aspx http://forum.codecall.net/topic/39818-tutorial-visual-studio-2008-obfuscating-with-dotfuscator/ 
0
Hi Akshay,
You cannot stop it.You can however obfuscate your code.You can buy an IL obfuscation tool. These tools work by 'optimising' the IL in such a way that reverse-engineering becomes much more difficult.
Of course if you are writing web services then reverse-engineering is not a problem as clients do not have access to your IL.
Thanks