Have you read http://support.microsoft.com/?kbid=307340 ? If not, I suggest you do so. If you need convincing or simply want to know why this problem occurs I suggest you keep reading. The problem described in the article above can cause your application...

If your application crashes, hangs and deadlocks it will cause/require the application pool to recycle in order to be resolved, but sometimes your application pool inexplicably recycles for no obvious reason. This is usually a configuration issue or due...