Q:

My application giving an exception once in a while

My asp.net application gives an exception once in a while as a result application pool stopped. and it needs to be started manually.
Does anyone know how to trace it, how to find what cause the problem?
I don't see any errors in Event Viewer.

A:

In IIS 7.0, events (configurable) and exceptions (always) are logged to the Windows event log when an application pool recycles. 
Sccot Guthrie's round-up of Tess's related posts is great:

Outstanding Blog for Learning how to Debug ASP.NET App Issues (Memory Leaks, Crashes, Deadlocks, etc) 
ASP.NET 2.0 Crash case study: Unhandled exceptions

