We recently published a fix for the following problem:
You create a deployment project for a web application in Visual Studio 2010, set the deployment property RestartWWWService=false and deploy to a Windows 2003 server. http://msdn.microsoft.com/en-us/library/22f9106b.aspx
In this situation the w3wp.exe process will still be recycled even though the RestartWWWService is set to false.
The fix is available here and should only be installed on development machines if you experience this problem.
Have a good one, Tess