如何以编程方式回收.net Web应用程序自己的apppool？

I have a complex server application that uses Nhibernate and Linq2SQL. About 3 times per day the Linq2sql code generates a "value cannot be null" exception. Once this happens, the code will always generate the exception. Diagnosis and solving the root cause will be lengthy and will introduce instability. I have a complex server application that uses N