NCover crashes when using with IIS

I am using NCover to test an asp.net web application hosted in IIS. it crashes almost everytime after my web application is launched and used for a few minutes, the Coverage.xml file did not get updated, The error is Object reference not set to an instance of an object, see details below. Is there any thing I did wrong?

C:\Program Files\NCover>ncover.console //iis
NCover.Console v1.5.5 - Code Coverage Analysis for .NET
Copyright (c) 2004-2005 Peter Waldschmidt

Command:
Command Args:
Working Directory:
Assemblies:
Coverage Xml: Coverage.Xml
Coverage Log: Coverage.Log

Waiting for profiled application to connect...Connected
Configuring Profiler...
Program Output
Object reference not set to an instance of an object.
^C
C:\Program Files\NCover>

Re: NCover Coverage report.

Have you checked your coverage exclusions in the NCoverExplorer options to make sure it is not accidentally being excluded?

Do you have an "Excluded" node in the tree containing the results?

In the coverage.xml file produced, are there entries for that assembly?