A: 

UPDATE: As I suspected ... having more than one site in IIS was root cause of trouble, Once I uninstalled Sharepoint Server 2010 and its web sites from IIS, my Visual Studio 2010 debugger was able to "Auto-Attach" w3wp.exe process while debugging any application ... ( I really don't see any reason that even after disabling all other websites why still it was giving me error at first place ?? )

I know its not a solution, because I have to remove Sharepoint Server ... but at present its more important for me to work on that application then Sharepoint Server.

But I am still open for any suggestions which might help me to run both together ....

Thanks,

Jack

JackLocke
Best practice for SharePoint is to run it in a VM, which could mean you avoid this issue.
Alex
A: 

Check the Bug fix for this issue in the Microsoft's Connect site.

.

Is it with .NET 3.5 in Visual Studio 2010 , if yes , then check http://www.ginktage.com/2010/08/fix-for-visual-studio-2010-hangs-when-debugging-asp-net-3-5-web-application/ for information

Senthil Kumar B