Attach to Process is not working in Visual studio 2008 in Windows 7

Today i had a wired issues with Visual Studio 2008 SP1 running in Windows 7 32bit Machine with IIS7 installed.
I am developing a web application. I have set up the default website in local host in IIS (IIS 7.0) to run the website and it is working fine when i press F5,the process runs and show break point locations. But when I try to debug the site by selecting attach to process from debug menu and select the browser process (IE8 or Mozilla), nothing happens and the process doesn't hit the break point. What am I doing wrong?

Thanks in advance for the help.

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