Windows Azure, just like any other IIS website can crash if an unhandled exception occurs. One way that this can happen is if you are calling an Async function call and in the function that is called on completion, you throw an exception.
In this situation, you will see something in the Application event log that looks like this:
Note: you may not see both of these errors but either or both of them point to the same problem.
Go to the complete details ...