Worker process recycling drops application session state
Applies To: Windows Server 2003, Windows Server 2003 R2, Windows Server 2003 with SP1
By default, Worker Processes recycle after a preconfigured amount of time. If your ASP applications are not designed to store session state while a worker process is recycled, then session state in that ASP application can be lost. To remedy this problem, you can either store session state in a database or disable worker process recycling.
Procedures
To disable worker process recycling
In IIS Manager, expand the local computer, expand Application Pools, right-click the application pool, and then click Properties.
On the Recycling tab, clear the Recycle worker processes (in minutes) check box.
Click OK.