Faced a classic problem and still the desired solution is pending. But I am sure this will help all! While working on a web application, one of my team presented some weird behaviour on ASP.NET FIrst observation: Session times out randomly while working on the application. So we started observing the application closely to see what might be causing this. We came out with some more observations: Detailed observation: Session times out when any of the user participates in certain scenario. Also, not only the specific session expires, but all the use sessions are expired. Further study shown that actually the app domain itself recycles. We studied the activities in these specific scenario. We found that a certain implementation use to create folder, put some temporrary files inside it and once done, the folder and the files were deleted. The application recycles whenever the folder is deleted. Do know more about it.